From 3328dab8006d0568381b4553bd0a153ec7af1a54 Mon Sep 17 00:00:00 2001
From: "Paul A. Jungwirth" <pj@illuminatedcomputing.com>
Date: Sat, 9 Jan 2021 21:59:43 -0800
Subject: [PATCH v28 9/9] Add PERIODs

- Added parsing for SQL:2011 syntax to define an application-time PERIOD on a
  table (in both CREATE TABLE and ALTER TABLE). Make sure we create the PERIOD
  after columns are known (since PERIODs can refer to them) but before
  constraints are handled (since PERIODs can appear in them).
- Added ALTER TABLE DROP support for PERIODs.
- Created postgres.pg_period table.
- Created information_schema.periods view.
- Added pg_dump support.
- Added tests and documentation.
- Automatically define a constraint for each PERIOD requiring the start column
  to be less than the end column.
- When creating a PERIOD, choose an appropriate range type we can use to
  implement PERIOD-related operations. You can choose one explicitly if there
  is ambiguity (due to multiple range types created over the same base type).
---
 doc/src/sgml/catalogs.sgml                    |  112 ++
 doc/src/sgml/ddl.sgml                         |   58 +
 doc/src/sgml/information_schema.sgml          |   63 +
 doc/src/sgml/ref/alter_table.sgml             |   25 +
 doc/src/sgml/ref/comment.sgml                 |    2 +
 doc/src/sgml/ref/create_table.sgml            |   59 +-
 doc/src/sgml/ref/delete.sgml                  |    3 +-
 doc/src/sgml/ref/update.sgml                  |    3 +-
 src/backend/catalog/Makefile                  |    1 +
 src/backend/catalog/aclchk.c                  |    2 +
 src/backend/catalog/dependency.c              |   17 +
 src/backend/catalog/heap.c                    |   75 +
 src/backend/catalog/information_schema.sql    |   23 +-
 src/backend/catalog/meson.build               |    1 +
 src/backend/catalog/objectaddress.c           |   73 +
 src/backend/catalog/pg_period.c               |  132 ++
 src/backend/catalog/sql_features.txt          |    2 +-
 src/backend/commands/alter.c                  |    1 +
 src/backend/commands/comment.c                |   10 +
 src/backend/commands/dropcmds.c               |    1 +
 src/backend/commands/event_trigger.c          |    4 +
 src/backend/commands/seclabel.c               |    1 +
 src/backend/commands/tablecmds.c              |  863 +++++++++-
 src/backend/commands/view.c                   |    4 +-
 src/backend/executor/nodeModifyTable.c        |   42 +-
 src/backend/nodes/nodeFuncs.c                 |    3 +
 src/backend/parser/analyze.c                  |   99 +-
 src/backend/parser/gram.y                     |   45 +-
 src/backend/parser/parse_relation.c           |   10 +
 src/backend/parser/parse_utilcmd.c            |  147 +-
 src/backend/utils/adt/Makefile                |    1 +
 src/backend/utils/adt/period.c                |   56 +
 src/backend/utils/cache/lsyscache.c           |   87 +
 src/bin/pg_dump/pg_backup_archiver.c          |    1 +
 src/bin/pg_dump/pg_dump.c                     |  175 +-
 src/bin/pg_dump/pg_dump.h                     |   15 +
 src/bin/pg_dump/pg_dump_sort.c                |    7 +
 src/bin/psql/describe.c                       |   36 +
 src/include/catalog/Makefile                  |    1 +
 src/include/catalog/dependency.h              |    1 +
 src/include/catalog/heap.h                    |    4 +
 src/include/catalog/meson.build               |    1 +
 src/include/catalog/pg_index.h                |    1 -
 src/include/catalog/pg_period.h               |   58 +
 src/include/catalog/pg_range.h                |    2 +
 src/include/commands/tablecmds.h              |    4 +-
 src/include/nodes/parsenodes.h                |   40 +-
 src/include/nodes/primnodes.h                 |    2 +
 src/include/parser/kwlist.h                   |    2 +-
 src/include/parser/parse_utilcmd.h            |    1 +
 src/include/utils/lsyscache.h                 |    3 +
 src/include/utils/period.h                    |   21 +
 .../test_ddl_deparse/test_ddl_deparse.c       |    6 +
 src/test/regress/expected/for_portion_of.out  |   38 +
 src/test/regress/expected/generated.out       |    4 +-
 src/test/regress/expected/periods.out         |  267 ++++
 .../regress/expected/without_overlaps.out     | 1419 +++++++++++++++++
 src/test/regress/parallel_schedule            |    2 +-
 src/test/regress/sql/for_portion_of.sql       |   32 +
 src/test/regress/sql/periods.sql              |  178 +++
 src/test/regress/sql/without_overlaps.sql     |  916 +++++++++++
 61 files changed, 5206 insertions(+), 56 deletions(-)
 create mode 100644 src/backend/catalog/pg_period.c
 create mode 100644 src/backend/utils/adt/period.c
 create mode 100644 src/include/catalog/pg_period.h
 create mode 100644 src/include/utils/period.h
 create mode 100644 src/test/regress/expected/periods.out
 create mode 100644 src/test/regress/sql/periods.sql

diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 6cc127618cd..977333370d0 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -230,6 +230,11 @@
       <entry>information about partition key of tables</entry>
      </row>
 
+     <row>
+      <entry><link linkend="catalog-pg-period"><structname>pg_period</structname></link></entry>
+      <entry>periods</entry>
+     </row>
+
      <row>
       <entry><link linkend="catalog-pg-policy"><structname>pg_policy</structname></link></entry>
       <entry>row-security policies</entry>
@@ -5738,6 +5743,113 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
        are simple references.
       </para></entry>
      </row>
+
+    </tbody>
+   </tgroup>
+  </table>
+ </sect1>
+
+
+ <sect1 id="catalog-pg-period">
+  <title><structname>pg_period</structname></title>
+
+  <indexterm zone="catalog-pg-period">
+   <primary>pg_period</primary>
+  </indexterm>
+
+  <para>
+   The catalog <structname>pg_period</structname> stores
+   information about system and application time periods.
+  </para>
+
+  <para>
+   Periods are described in <xref linkend="ddl-periods"/>.
+  </para>
+
+  <table>
+   <title><structname>pg_period</structname> Columns</title>
+
+   <tgroup cols="1">
+    <thead>
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       Column Type
+      </para>
+      <para>
+       Description
+      </para></entry>
+     </row>
+    </thead>
+
+    <tbody>
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>oid</structfield> <type>oid</type>
+      </para>
+      <para>
+       Row identifier
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>pername</structfield> <type>text</type>
+      </para>
+      <para>
+       Period name
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>perrelid</structfield> <type>oid</type>
+       (references <link linkend="catalog-pg-class"><structname>pg_class</structname></link>.<structfield>oid</structfield>)
+      </para>
+      <para>
+       The table this period belongs to
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>perstart</structfield> <type>int2</type>
+       (references <link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.<structfield>attnum</structfield>)
+      </para>
+      <para>
+       The number of the start column
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>perend</structfield> <type>int2</type>
+       (references <link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.<structfield>attnum</structfield>)
+      </para>
+      <para>
+       The number of the end column
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>perrange</structfield> <type>int2</type>
+       (references <link linkend="catalog-pg-attribute"><structname>pg_attribute</structname></link>.<structfield>attnum</structfield>)
+      </para>
+      <para>
+       The number of the <literal>GENERATED</literal> column that implements the <literal>PERIOD</literal>.
+      </para></entry>
+     </row>
+
+     <row>
+      <entry role="catalog_table_entry"><para role="column_definition">
+       <structfield>perconstraint</structfield> <type>oid</type>
+       (references <link linkend="catalog-pg-constraint"><structname>pg_constraint</structname></link>.<structfield>oid</structfield>)
+      </para>
+      <para>
+       The OID of the period's <literal>CHECK</literal> constraint
+      </para></entry>
+     </row>
+
     </tbody>
    </tgroup>
   </table>
diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 8616a8e9cc9..6269fb79b4b 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -1375,6 +1375,64 @@ CREATE TABLE circles (
   </sect2>
  </sect1>
 
+ <sect1 id="ddl-periods">
+  <title>Periods</title>
+
+  <para>
+   Periods are definitions on a table that associate a period name with a start
+   column and an end column.  Both columns must be of exactly the same type
+   (including collation), have a btree operator class, and the start column
+   value must be strictly less than the end column value.
+  </para>
+
+  <para>
+   There are two types of periods: application and system.  System periods are
+   distinguished by their name which must be <literal>SYSTEM_TIME</literal>.  Any
+   other name is an application period.
+  </para>
+
+  <sect2 id="ddl-periods-application-periods">
+  <title>Application Periods</title>
+
+   <indexterm>
+    <primary>period</primary>
+    <secondary>application</secondary>
+   </indexterm>
+
+   <para>
+    Application periods are defined on a table using the following syntax:
+   </para>
+
+<programlisting>
+CREATE TABLE billing_addresses (
+  customer_id integer,
+  address_id integer,
+  valid_from date,
+  valid_to date,
+  <emphasis>PERIOD FOR validity (valid_from, valid_to)</emphasis>
+);
+</programlisting>
+
+   <para>
+    Application periods can be used to define temporal primary and foreign keys.
+    Any table with a temporal primary key is a temporal table and supports temporal update and delete commands.
+   </para>
+  </sect2>
+
+  <sect2 id="ddl-periods-system-periods">
+   <title>System Periods</title>
+
+   <indexterm>
+    <primary>period</primary>
+    <secondary>system</secondary>
+   </indexterm>
+
+   <para>
+    Periods for <literal>SYSTEM_TIME</literal> are currently not implemented.
+   </para>
+  </sect2>
+ </sect1>
+
  <sect1 id="ddl-system-columns">
   <title>System Columns</title>
 
diff --git a/doc/src/sgml/information_schema.sgml b/doc/src/sgml/information_schema.sgml
index 9e66be4e83d..558cc7b3f15 100644
--- a/doc/src/sgml/information_schema.sgml
+++ b/doc/src/sgml/information_schema.sgml
@@ -4171,6 +4171,69 @@ ORDER BY c.ordinal_position;
   </table>
  </sect1>
 
+ <sect1 id="infoschema-periods">
+  <title><literal>periods</literal></title>
+
+  <para>
+   The view <literal>parameters</literal> contains information about the
+   periods of all tables in the current database.  The start and end column
+   names are only shown if the current user has access to them (by way of being
+   the owner or having some privilege).
+  </para>
+
+  <table>
+   <title><literal>periods</literal> Columns</title>
+
+   <tgroup cols="3">
+    <thead>
+     <row>
+      <entry>Name</entry>
+      <entry>Data Type</entry>
+      <entry>Description</entry>
+     </row>
+    </thead>
+
+    <tbody>
+     <row>
+      <entry><literal>table_catalog</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the database containing the period (always the current database)</entry>
+     </row>
+
+     <row>
+      <entry><literal>table_schema</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the schema containing the period</entry>
+     </row>
+
+     <row>
+      <entry><literal>table_name</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the table containing the period</entry>
+     </row>
+
+     <row>
+      <entry><literal>period_name</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the period</entry>
+     </row>
+
+     <row>
+      <entry><literal>start_column_name</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the start column for the period</entry>
+     </row>
+
+     <row>
+      <entry><literal>end_column_name</literal></entry>
+      <entry><type>sql_identifier</type></entry>
+      <entry>Name of the end column for the period</entry>
+     </row>
+    </tbody>
+   </tgroup>
+  </table>
+ </sect1>
+
  <sect1 id="infoschema-referential-constraints">
   <title><literal>referential_constraints</literal></title>
 
diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 96e3d776051..acd11922a4c 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -61,6 +61,8 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
     ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
     VALIDATE CONSTRAINT <replaceable class="parameter">constraint_name</replaceable>
     DROP CONSTRAINT [ IF EXISTS ]  <replaceable class="parameter">constraint_name</replaceable> [ RESTRICT | CASCADE ]
+    ADD PERIOD FOR <replaceable class="parameter">period_name</replaceable> ( <replaceable class="parameter">start_column</replaceable>, <replaceable class="parameter">end_column</replaceable> ) [ WITH ( <replaceable class="parameter">period_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] ) ]
+    DROP PERIOD FOR <replaceable class="parameter">period_name</replaceable> [ RESTRICT | CASCADE ]
     DISABLE TRIGGER [ <replaceable class="parameter">trigger_name</replaceable> | ALL | USER ]
     ENABLE TRIGGER [ <replaceable class="parameter">trigger_name</replaceable> | ALL | USER ]
     ENABLE REPLICA TRIGGER <replaceable class="parameter">trigger_name</replaceable>
@@ -585,6 +587,29 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry id="sql-altertable-desc-add-period">
+    <term><literal>ADD PERIOD FOR</literal></term>
+    <listitem>
+     <para>
+      This form adds a new period to a table using the same syntax as
+      <xref linkend="sql-createtable"/>.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry id="sql-altertable-desc-drop-period">
+    <term><literal>DROP PERIOD FOR</literal></term>
+    <listitem>
+     <para>
+      This form drops the specified period on a table.  The start and end
+      columns will not be dropped by this command but the
+      <literal>CHECK</literal> constraint will be.  You will need to say
+      <literal>CASCADE</literal> if anything outside the table depends on the
+      column.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry id="sql-altertable-desc-disable-enable-trigger">
     <term><literal>DISABLE</literal>/<literal>ENABLE [ REPLICA | ALWAYS ] TRIGGER</literal></term>
     <listitem>
diff --git a/doc/src/sgml/ref/comment.sgml b/doc/src/sgml/ref/comment.sgml
index 5b43c56b133..49c2df99449 100644
--- a/doc/src/sgml/ref/comment.sgml
+++ b/doc/src/sgml/ref/comment.sgml
@@ -44,6 +44,7 @@ COMMENT ON
   OPERATOR <replaceable class="parameter">operator_name</replaceable> (<replaceable class="parameter">left_type</replaceable>, <replaceable class="parameter">right_type</replaceable>) |
   OPERATOR CLASS <replaceable class="parameter">object_name</replaceable> USING <replaceable class="parameter">index_method</replaceable> |
   OPERATOR FAMILY <replaceable class="parameter">object_name</replaceable> USING <replaceable class="parameter">index_method</replaceable> |
+  PERIOD <replaceable class="parameter">relation_name</replaceable>.<replaceable class="parameter">period_name</replaceable> |
   POLICY <replaceable class="parameter">policy_name</replaceable> ON <replaceable class="parameter">table_name</replaceable> |
   [ PROCEDURAL ] LANGUAGE <replaceable class="parameter">object_name</replaceable> |
   PROCEDURE <replaceable class="parameter">procedure_name</replaceable> [ ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] ) ] |
@@ -341,6 +342,7 @@ COMMENT ON OPERATOR ^ (text, text) IS 'Performs intersection of two texts';
 COMMENT ON OPERATOR - (NONE, integer) IS 'Unary minus';
 COMMENT ON OPERATOR CLASS int4ops USING btree IS '4 byte integer operators for btrees';
 COMMENT ON OPERATOR FAMILY integer_ops USING btree IS 'all integer operators for btrees';
+COMMENT ON PERIOD my_table.my_column IS 'Sales promotion validity';
 COMMENT ON POLICY my_policy ON mytable IS 'Filter rows by users';
 COMMENT ON PROCEDURE my_proc (integer, integer) IS 'Runs a report';
 COMMENT ON PUBLICATION alltables IS 'Publishes all operations on all tables';
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index a649898fed6..53f56a6f3fb 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -23,6 +23,7 @@ PostgreSQL documentation
 <synopsis>
 CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="parameter">table_name</replaceable> ( [
   { <replaceable class="parameter">column_name</replaceable> <replaceable class="parameter">data_type</replaceable> [ STORAGE { PLAIN | EXTERNAL | EXTENDED | MAIN | DEFAULT } ] [ COMPRESSION <replaceable>compression_method</replaceable> ] [ COLLATE <replaceable>collation</replaceable> ] [ <replaceable class="parameter">column_constraint</replaceable> [ ... ] ]
+    | <replaceable>period_definition</replaceable>
     | <replaceable>table_constraint</replaceable>
     | LIKE <replaceable>source_table</replaceable> [ <replaceable>like_option</replaceable> ... ] }
     [, ... ]
@@ -37,6 +38,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
 CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="parameter">table_name</replaceable>
     OF <replaceable class="parameter">type_name</replaceable> [ (
   { <replaceable class="parameter">column_name</replaceable> [ WITH OPTIONS ] [ <replaceable class="parameter">column_constraint</replaceable> [ ... ] ]
+    | <replaceable>period_definition</replaceable>
     | <replaceable>table_constraint</replaceable> }
     [, ... ]
 ) ]
@@ -49,6 +51,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
 CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="parameter">table_name</replaceable>
     PARTITION OF <replaceable class="parameter">parent_table</replaceable> [ (
   { <replaceable class="parameter">column_name</replaceable> [ WITH OPTIONS ] [ <replaceable class="parameter">column_constraint</replaceable> [ ... ] ]
+    | <replaceable>period_definition</replaceable>
     | <replaceable>table_constraint</replaceable> }
     [, ... ]
 ) ] { FOR VALUES <replaceable class="parameter">partition_bound_spec</replaceable> | DEFAULT }
@@ -73,6 +76,11 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
 
+<phrase>and <replaceable class="parameter">period_definition</replaceable> is:</phrase>
+
+PERIOD FOR { <replaceable class="parameter">period_name</replaceable> | SYSTEM_TIME } ( <replaceable class="parameter">column_name</replaceable>, <replaceable class="parameter">column_name</replaceable> )
+[ WITH ( <replaceable class="parameter">period_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] ) ]
+
 <phrase>and <replaceable class="parameter">table_constraint</replaceable> is:</phrase>
 
 [ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ]
@@ -81,7 +89,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
   UNIQUE [ NULLS [ NOT ] DISTINCT ] ( <replaceable class="parameter">column_name</replaceable> [, ... ] [, <replaceable class="parameter">column_name</replaceable> WITHOUT OVERLAPS ] ) <replaceable class="parameter">index_parameters</replaceable> |
   PRIMARY KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] [, <replaceable class="parameter">column_name</replaceable> WITHOUT OVERLAPS ] ) <replaceable class="parameter">index_parameters</replaceable> |
   EXCLUDE [ USING <replaceable class="parameter">index_method</replaceable> ] ( <replaceable class="parameter">exclude_element</replaceable> WITH <replaceable class="parameter">operator</replaceable> [, ... ] ) <replaceable class="parameter">index_parameters</replaceable> [ WHERE ( <replaceable class="parameter">predicate</replaceable> ) ] |
-  FOREIGN KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] [, PERIOD <replaceable class="parameter">column_name</replaceable> ] ) REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] [, PERIOD <replaceable class="parameter">column_name</replaceable> ] ) ]
+  FOREIGN KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] [, PERIOD { <replaceable class="parameter">column_name</replaceable> | <replaceable class="parameter">period_name</replaceable> } ] ) REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] [, PERIOD { <replaceable class="parameter">column_name</replaceable> | <replaceable class="parameter">period_name</replaceable> } ] ) ]
     [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE <replaceable
 class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
@@ -140,6 +148,14 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
    name as any existing data type in the same schema.
   </para>
 
+  <para>
+   Periods my be defined on tables, specifying that two existing columns
+   represent start and end values for the period.  Periods may have any name
+   that doesn't conflict with a column name, but the name
+   <literal>SYSTEM_TIME</literal> is special, used for versioning tables.
+   System periods are not yet implemented.  See <xref linkend="ddl-periods"/> for more details.
+  </para>
+
   <para>
    The optional constraint clauses specify constraints (tests) that
    new or updated rows must satisfy for an insert or update operation
@@ -800,6 +816,37 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
     </listitem>
    </varlistentry>
 
+   <varlistentry id="sql-createtable-parms-period">
+    <term><literal>PERIOD FOR <replaceable class="parameter">period_name</replaceable> ( <replaceable class="parameter">column_name</replaceable>, <replaceable class="parameter">column_name</replaceable> ) [ WITH ( <replaceable class="parameter">period_option</replaceable> = <replaceable class="parameter">value</replaceable> [, ... ] ) ]</literal></term>
+    <listitem>
+     <para>
+      A period definition gives semantic meaning to two existing columns of
+      the table.  It defines a "start column" and an "end column" where the
+      start value is strictly less than the end value.  A
+      <literal>CHECK</literal> constraint is automatically created to enforce
+      this. You can specify the name of that constraint with the
+      <literal>check_constraint_name</literal> <replaceable class="parameter">period_option</replaceable>.
+     </para>
+
+     <para>
+      Both columns must have exactly the same type and must have a range type
+      defined from their base type.  If there are several range types for that
+      base type, you must specify which one you want by using the
+      <literal>rangetype</literal> <replaceable class="parameter">period_option</replaceable>.
+      Any base type is allowed, as long as it has a range type, although it is
+      expected that most periods will use temporal types like <literal>timestamptz</literal>
+      or <literal>date</literal>.
+     </para>
+
+     <para>
+      A hidden <literal>GENERATED</literal> column is used to implement the period,
+      with the same name as the period.  If such a column already exists, you
+      can use the <literal>colexists</literal> <replaceable class="parameter">period_option</replaceable>
+      with value <literal>true</literal> to avoid creating it.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry id="sql-createtable-parms-constraint">
     <term><literal>CONSTRAINT <replaceable class="parameter">constraint_name</replaceable></literal></term>
     <listitem>
@@ -1152,8 +1199,8 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
    <varlistentry id="sql-createtable-parms-references">
     <term><literal>REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH <replaceable class="parameter">matchtype</replaceable> ] [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ] [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ]</literal> (column constraint)</term>
 
-   <term><literal>FOREIGN KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] [, PERIOD <replaceable class="parameter">column_name</replaceable> ] )
-    REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] [, PERIOD <replaceable class="parameter">column_name</replaceable> ] ) ]
+   <term><literal>FOREIGN KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] [, PERIOD { <replaceable class="parameter">column_name</replaceable> | <replaceable class="parameter">period_name</replaceable> } ] )
+    REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] [, PERIOD { <replaceable class="parameter">column_name</replaceable> | <replaceable class="parameter">period_name</replaceable> } ] ) ]
     [ MATCH <replaceable class="parameter">matchtype</replaceable> ]
     [ ON DELETE <replaceable class="parameter">referential_action</replaceable> ]
     [ ON UPDATE <replaceable class="parameter">referential_action</replaceable> ]</literal>
@@ -1174,7 +1221,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
      </para>
 
      <para>
-      If the last column is marked with <literal>PERIOD</literal>,
+      If the last key part is marked with <literal>PERIOD</literal>,
       it is treated in a special way.
       While the non-<literal>PERIOD</literal> columns are compared for equality
       (and there must be at least one of them),
@@ -1185,7 +1232,9 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
       whose combined <literal>PERIOD</literal> values completely cover
       the referencing record's.
       In other words, the reference must have a referent for its entire duration.
-      Normally this column would be a range or multirange type,
+      Normally this part would be either a
+      <link linkend="sql-createtable-parms-period"><literal>PERIOD</literal></link>
+      or a column with a range or multirange type,
       although any type whose GiST opclass has a "contained by" operator
       and a <literal>referencedagg</literal> support function is allowed.
       (See <xref linkend="gist-extensibility"/>.)
diff --git a/doc/src/sgml/ref/delete.sgml b/doc/src/sgml/ref/delete.sgml
index 1c7275341ea..b388be7508c 100644
--- a/doc/src/sgml/ref/delete.sgml
+++ b/doc/src/sgml/ref/delete.sgml
@@ -56,7 +56,8 @@ DELETE FROM [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ *
   </para>
 
   <para>
-   If the table has a range or multirange column,
+   If the table has a range or multirange column, or a
+   <link linkend="ddl-periods-application-periods"><literal>PERIOD</literal></link>,
    you may supply a <literal>FOR PORTION OF</literal> clause, and your delete will
    only affect rows that overlap the given interval. Furthermore, if a row's span
    extends outside the <literal>FOR PORTION OF</literal> bounds, then your delete
diff --git a/doc/src/sgml/ref/update.sgml b/doc/src/sgml/ref/update.sgml
index 71a02697f2d..a1b88571d0a 100644
--- a/doc/src/sgml/ref/update.sgml
+++ b/doc/src/sgml/ref/update.sgml
@@ -53,7 +53,8 @@ UPDATE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] [
   </para>
 
   <para>
-   If the table has a range or multirange column,
+   If the table has a range or multirange column, or a
+   <link linkend="ddl-periods-application-periods"><literal>PERIOD</literal></link>,
    you may supply a <literal>FOR PORTION OF</literal> clause, and your update will
    only affect rows that overlap the given interval. Furthermore, if a row's span
    extends outside the <literal>FOR PORTION OF</literal> bounds, then your update
diff --git a/src/backend/catalog/Makefile b/src/backend/catalog/Makefile
index 1589a75fd53..3b7af965032 100644
--- a/src/backend/catalog/Makefile
+++ b/src/backend/catalog/Makefile
@@ -39,6 +39,7 @@ OBJS = \
 	pg_namespace.o \
 	pg_operator.o \
 	pg_parameter_acl.o \
+	pg_period.o \
 	pg_proc.o \
 	pg_publication.o \
 	pg_range.o \
diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 7abf3c2a74a..3f03efe9e3d 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -2810,6 +2810,7 @@ aclcheck_error(AclResult aclerr, ObjectType objtype,
 					case OBJECT_DEFAULT:
 					case OBJECT_DEFACL:
 					case OBJECT_DOMCONSTRAINT:
+					case OBJECT_PERIOD:
 					case OBJECT_PUBLICATION_NAMESPACE:
 					case OBJECT_PUBLICATION_REL:
 					case OBJECT_ROLE:
@@ -2951,6 +2952,7 @@ aclcheck_error(AclResult aclerr, ObjectType objtype,
 					case OBJECT_DEFACL:
 					case OBJECT_DOMCONSTRAINT:
 					case OBJECT_PARAMETER_ACL:
+					case OBJECT_PERIOD:
 					case OBJECT_PUBLICATION_NAMESPACE:
 					case OBJECT_PUBLICATION_REL:
 					case OBJECT_ROLE:
diff --git a/src/backend/catalog/dependency.c b/src/backend/catalog/dependency.c
index eadcf6af0df..6b72f0841fc 100644
--- a/src/backend/catalog/dependency.c
+++ b/src/backend/catalog/dependency.c
@@ -48,6 +48,7 @@
 #include "catalog/pg_operator.h"
 #include "catalog/pg_opfamily.h"
 #include "catalog/pg_parameter_acl.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_policy.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_publication.h"
@@ -622,6 +623,15 @@ findDependentObjects(const ObjectAddress *object,
 						return;
 					}
 
+					/*
+					 * If a table attribute is an internal part of something else
+					 * (e.g. the GENERATED column used by a PERIOD),
+					 * and we are deleting the whole table,
+					 * then it's okay.
+					 */
+					if (foundDep->objsubid && !object->objectSubId)
+						break;
+
 					/*
 					 * We postpone actually issuing the error message until
 					 * after this loop, so that we can make the behavior
@@ -1394,6 +1404,10 @@ doDeletion(const ObjectAddress *object, int flags)
 			RemoveConstraintById(object->objectId);
 			break;
 
+		case OCLASS_PERIOD:
+			RemovePeriodById(object->objectId);
+			break;
+
 		case OCLASS_DEFAULT:
 			RemoveAttrDefaultById(object->objectId);
 			break;
@@ -2810,6 +2824,9 @@ getObjectClass(const ObjectAddress *object)
 		case ConstraintRelationId:
 			return OCLASS_CONSTRAINT;
 
+		case PeriodRelationId:
+			return OCLASS_PERIOD;
+
 		case ConversionRelationId:
 			return OCLASS_CONVERSION;
 
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 5e773740f4d..aea94e0bcdf 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -49,6 +49,7 @@
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_opclass.h"
 #include "catalog/pg_partitioned_table.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_statistic.h"
 #include "catalog/pg_subscription_rel.h"
 #include "catalog/pg_tablespace.h"
@@ -2044,6 +2045,80 @@ SetAttrMissing(Oid relid, char *attname, char *value)
 	table_close(tablerel, AccessExclusiveLock);
 }
 
+/*
+ * Store a period of relation rel.
+ *
+ * Returns the OID of the new pg_period tuple.
+ */
+Oid
+StorePeriod(Relation rel, const char *periodname, AttrNumber startnum,
+			AttrNumber endnum, AttrNumber rangenum, Oid conoid)
+{
+	Datum		values[Natts_pg_period];
+	bool		nulls[Natts_pg_period];
+	Relation	pg_period;
+	HeapTuple	tuple;
+	Oid			oid;
+	NameData	pername;
+	ObjectAddress	myself, referenced;
+
+	Assert(rangenum != InvalidAttrNumber);
+
+	namestrcpy(&pername, periodname);
+
+	MemSet(values, 0, sizeof(values));
+	MemSet(nulls, false, sizeof(nulls));
+
+	pg_period = table_open(PeriodRelationId, RowExclusiveLock);
+
+	oid = GetNewOidWithIndex(pg_period, AttrDefaultOidIndexId, Anum_pg_period_oid);
+	values[Anum_pg_period_oid - 1] = ObjectIdGetDatum(oid);
+	values[Anum_pg_period_pername - 1] = NameGetDatum(&pername);
+	values[Anum_pg_period_perrelid - 1] = RelationGetRelid(rel);
+	values[Anum_pg_period_perstart - 1] = startnum;
+	values[Anum_pg_period_perend - 1] = endnum;
+	values[Anum_pg_period_perrange - 1] = rangenum;
+	values[Anum_pg_period_perconstraint - 1] = conoid;
+
+	tuple = heap_form_tuple(RelationGetDescr(pg_period), values, nulls);
+	CatalogTupleInsert(pg_period, tuple);
+
+	ObjectAddressSet(myself, PeriodRelationId, oid);
+
+	/* Drop the period when the table is dropped. */
+	ObjectAddressSet(referenced, RelationRelationId, RelationGetRelid(rel));
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
+
+	/* Forbid dropping the columns of the period. */
+	ObjectAddressSubSet(referenced, RelationRelationId, RelationGetRelid(rel), startnum);
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	ObjectAddressSubSet(referenced, RelationRelationId, RelationGetRelid(rel), endnum);
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+
+	/*
+	 * The range column is an implementation detail,
+	 * but we can't use DEPENDENCY_INTERNAL
+	 * because dropping the table will check for dependencies on all subobjects too
+	 * (in findDependentObjects).
+	 * But if we make an AUTO dependency one way we will auto-drop the column
+	 * when we drop the PERIOD,
+	 * and a NORMAL dependency the other way we will forbid dropping the column directly.
+	 */
+	ObjectAddressSubSet(referenced, RelationRelationId, RelationGetRelid(rel), rangenum);
+	recordDependencyOn(&referenced, &myself, DEPENDENCY_INTERNAL);
+
+	/*
+	 * The constraint is an implementation detail, so we mark it as such.
+	 * (Note that myself and referenced are reversed for this one.)
+	 */
+	ObjectAddressSet(referenced, ConstraintRelationId, conoid);
+	recordDependencyOn(&referenced, &myself, DEPENDENCY_INTERNAL);
+
+	table_close(pg_period, RowExclusiveLock);
+
+	return oid;
+}
+
 /*
  * Store a check-constraint expression for the given relation.
  *
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index c402ae72741..50ca0d05f87 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -1207,7 +1207,28 @@ GRANT SELECT ON parameters TO PUBLIC;
  * PERIODS view
  */
 
--- feature not supported
+CREATE VIEW periods AS
+    SELECT current_database()::information_schema.sql_identifier AS table_catalog,
+           nc.nspname::information_schema.sql_identifier AS table_schema,
+           c.relname::information_schema.sql_identifier AS table_name,
+           p.pername::information_schema.sql_identifier AS period_name,
+           CASE WHEN pg_has_role(c.relowner, 'USAGE')
+                  OR has_column_privilege(sa.attrelid, sa.attnum, 'SELECT, INSERT, UPDATE, REFERENCES')
+                THEN sa.attname::information_schema.sql_identifier
+           END AS start_column_name,
+           CASE WHEN pg_has_role(c.relowner, 'USAGE')
+                  OR has_column_privilege(ea.attrelid, ea.attnum, 'SELECT, INSERT, UPDATE, REFERENCES')
+                THEN ea.attname::information_schema.sql_identifier
+           END AS end_column_name
+    FROM pg_period AS p
+    JOIN pg_class AS c ON c.oid = p.perrelid
+    JOIN pg_namespace AS nc ON nc.oid = c.relnamespace
+    JOIN pg_attribute AS sa ON (sa.attrelid, sa.attnum) = (p.perrelid, p.perstart)
+    JOIN pg_attribute AS ea ON (ea.attrelid, ea.attnum) = (p.perrelid, p.perend)
+    WHERE NOT pg_is_other_temp_schema(nc.oid)
+      AND c.relkind IN ('r', 'v');
+
+GRANT SELECT ON periods TO PUBLIC;
 
 
 /*
diff --git a/src/backend/catalog/meson.build b/src/backend/catalog/meson.build
index 2f3ded8a0e7..a372fb0aae8 100644
--- a/src/backend/catalog/meson.build
+++ b/src/backend/catalog/meson.build
@@ -26,6 +26,7 @@ backend_sources += files(
   'pg_namespace.c',
   'pg_operator.c',
   'pg_parameter_acl.c',
+  'pg_period.c',
   'pg_proc.c',
   'pg_publication.c',
   'pg_range.c',
diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index 360c6b2ba63..651a1c18684 100644
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -45,6 +45,7 @@
 #include "catalog/pg_operator.h"
 #include "catalog/pg_opfamily.h"
 #include "catalog/pg_parameter_acl.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_policy.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_publication.h"
@@ -733,6 +734,10 @@ static const struct object_type_map
 	{
 		"domain constraint", OBJECT_DOMCONSTRAINT
 	},
+	/* OCLASS_PERIOD */
+	{
+		"period", OBJECT_PERIOD
+	},
 	/* OCLASS_CONVERSION */
 	{
 		"conversion", OBJECT_CONVERSION
@@ -1011,6 +1016,7 @@ get_object_address(ObjectType objtype, Node *object,
 			case OBJECT_TRIGGER:
 			case OBJECT_TABCONSTRAINT:
 			case OBJECT_POLICY:
+			case OBJECT_PERIOD:
 				address = get_object_address_relobject(objtype, castNode(List, object),
 													   &relation, missing_ok);
 				break;
@@ -1509,6 +1515,13 @@ get_object_address_relobject(ObjectType objtype, List *object,
 				InvalidOid;
 			address.objectSubId = 0;
 			break;
+		case OBJECT_PERIOD:
+			address.classId = PeriodRelationId;
+			address.objectId = relation ?
+				get_relation_period_oid(reloid, depname, missing_ok) :
+				InvalidOid;
+			address.objectSubId = 0;
+			break;
 		default:
 			elog(ERROR, "unrecognized object type: %d", (int) objtype);
 	}
@@ -2326,6 +2339,7 @@ pg_get_object_address(PG_FUNCTION_ARGS)
 		case OBJECT_RULE:
 		case OBJECT_TRIGGER:
 		case OBJECT_TABCONSTRAINT:
+		case OBJECT_PERIOD:
 		case OBJECT_OPCLASS:
 		case OBJECT_OPFAMILY:
 			objnode = (Node *) name;
@@ -2436,6 +2450,7 @@ check_object_ownership(Oid roleid, ObjectType objtype, ObjectAddress address,
 		case OBJECT_TRIGGER:
 		case OBJECT_POLICY:
 		case OBJECT_TABCONSTRAINT:
+		case OBJECT_PERIOD:
 			if (!object_ownercheck(RelationRelationId, RelationGetRelid(relation), roleid))
 				aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
 							   RelationGetRelationName(relation));
@@ -3084,6 +3099,38 @@ getObjectDescription(const ObjectAddress *object, bool missing_ok)
 				break;
 			}
 
+		case OCLASS_PERIOD:
+			{
+				HeapTuple	perTup;
+				Form_pg_period per;
+
+				perTup = SearchSysCache1(PERIODOID,
+										 ObjectIdGetDatum(object->objectId));
+				if (!HeapTupleIsValid(perTup))
+					elog(ERROR, "cache lookup failed for period %u",
+						 object->objectId);
+				per = (Form_pg_period) GETSTRUCT(perTup);
+
+				if (OidIsValid(per->perrelid))
+				{
+					StringInfoData rel;
+
+					initStringInfo(&rel);
+					getRelationDescription(&rel, per->perrelid, false);
+					appendStringInfo(&buffer, _("period %s on %s"),
+									 NameStr(per->pername), rel.data);
+					pfree(rel.data);
+				}
+				else
+				{
+					appendStringInfo(&buffer, _("period %s"),
+									 NameStr(per->pername));
+				}
+
+				ReleaseSysCache(perTup);
+				break;
+			}
+
 		case OCLASS_CONVERSION:
 			{
 				HeapTuple	conTup;
@@ -4448,6 +4495,10 @@ getObjectTypeDescription(const ObjectAddress *object, bool missing_ok)
 										 missing_ok);
 			break;
 
+		case OCLASS_PERIOD:
+			appendStringInfoString(&buffer, "period");
+			break;
+
 		case OCLASS_CONVERSION:
 			appendStringInfoString(&buffer, "conversion");
 			break;
@@ -4955,6 +5006,28 @@ getObjectIdentityParts(const ObjectAddress *object,
 				break;
 			}
 
+		case OCLASS_PERIOD:
+			{
+				HeapTuple	perTup;
+				Form_pg_period per;
+
+				perTup = SearchSysCache1(PERIODOID,
+										 ObjectIdGetDatum(object->objectId));
+				if (!HeapTupleIsValid(perTup))
+					elog(ERROR, "cache lookup failed for period %u",
+						 object->objectId);
+				per = (Form_pg_period) GETSTRUCT(perTup);
+
+				appendStringInfo(&buffer, "%s on ",
+								 quote_identifier(NameStr(per->pername)));
+				getRelationIdentity(&buffer, per->perrelid, objname, false);
+				if (objname)
+					*objname = lappend(*objname, pstrdup(NameStr(per->pername)));
+
+				ReleaseSysCache(perTup);
+				break;
+			}
+
 		case OCLASS_CONVERSION:
 			{
 				HeapTuple	conTup;
diff --git a/src/backend/catalog/pg_period.c b/src/backend/catalog/pg_period.c
new file mode 100644
index 00000000000..465b5b675e3
--- /dev/null
+++ b/src/backend/catalog/pg_period.c
@@ -0,0 +1,132 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_period.c
+ *	  routines to support manipulation of the pg_period relation
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/catalog/pg_period.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "access/genam.h"
+#include "access/heapam.h"
+#include "access/htup_details.h"
+#include "catalog/indexing.h"
+#include "catalog/pg_period.h"
+#include "utils/fmgroids.h"
+#include "utils/lsyscache.h"
+#include "utils/rel.h"
+#include "utils/syscache.h"
+
+
+/*
+ * Delete a single period record.
+ */
+void
+RemovePeriodById(Oid periodId)
+{
+	Relation	pg_period;
+	HeapTuple	tup;
+
+	pg_period = table_open(PeriodRelationId, RowExclusiveLock);
+
+	tup = SearchSysCache1(PERIODOID, ObjectIdGetDatum(periodId));
+	if (!HeapTupleIsValid(tup)) /* should not happen */
+		elog(ERROR, "cache lookup failed for period %u", periodId);
+
+	/* Fry the period itself */
+	CatalogTupleDelete(pg_period, &tup->t_self);
+
+	/* Clean up */
+	ReleaseSysCache(tup);
+	table_close(pg_period, RowExclusiveLock);
+}
+
+/*
+ * get_relation_period_oid
+ *		Find a period on the specified relation with the specified name.
+ *		Returns period's OID.
+ */
+Oid
+get_relation_period_oid(Oid relid, const char *pername, bool missing_ok)
+{
+	Relation	pg_period;
+	HeapTuple	tuple;
+	SysScanDesc scan;
+	ScanKeyData skey[2];
+	Oid			perOid = InvalidOid;
+
+	/* Fetch the period tuple from pg_period. */
+	pg_period = table_open(PeriodRelationId, AccessShareLock);
+
+	ScanKeyInit(&skey[0],
+				Anum_pg_period_perrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(relid));
+	ScanKeyInit(&skey[1],
+				Anum_pg_period_pername,
+				BTEqualStrategyNumber, F_NAMEEQ,
+				CStringGetDatum(pername));
+
+	scan = systable_beginscan(pg_period, PeriodRelidNameIndexId, true,
+							  NULL, 2, skey);
+
+	/* There can be at most one matching row */
+	if (HeapTupleIsValid(tuple = systable_getnext(scan)))
+		perOid = ((Form_pg_period) GETSTRUCT(tuple))->oid;
+
+	systable_endscan(scan);
+
+	/* If no such period exists, complain */
+	if (!OidIsValid(perOid) && !missing_ok)
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+				 errmsg("period \"%s\" for table \"%s\" does not exist",
+						pername, get_rel_name(relid))));
+
+	table_close(pg_period, AccessShareLock);
+
+	return perOid;
+}
+
+/*
+ * get_period_attnos
+ *		Get the attno of the GENERATED rangetype column
+ *		for all PERIODs in this table.
+ */
+extern Bitmapset
+*get_period_attnos(Oid relid)
+{
+	Bitmapset *attnos = NULL;
+	Relation	pg_period;
+	HeapTuple	tuple;
+	SysScanDesc scan;
+	ScanKeyData skey[1];
+
+	pg_period = table_open(PeriodRelationId, AccessShareLock);
+
+	ScanKeyInit(&skey[0],
+				Anum_pg_period_perrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(relid));
+
+	scan = systable_beginscan(pg_period, PeriodRelidNameIndexId, true,
+							  NULL, 1, skey);
+
+	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+	{
+		Form_pg_period period = (Form_pg_period) GETSTRUCT(tuple);
+
+		attnos = bms_add_member(attnos, period->perrange);
+	}
+
+	systable_endscan(scan);
+	table_close(pg_period, AccessShareLock);
+
+	return attnos;
+}
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index 925d15a2c38..c93c69750ab 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -448,7 +448,7 @@ T176	Sequence generator support			NO	supported except for NEXT VALUE FOR
 T177	Sequence generator support: simple restart option			YES	
 T178	Identity columns: simple restart option			YES	
 T180	System-versioned tables			NO	
-T181	Application-time period tables			NO	
+T181	Application-time period tables			YES	
 T191	Referential action RESTRICT			YES	
 T200	Trigger DDL			NO	similar but not fully compatible
 T201	Comparable data types for referential constraints			YES	
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index cd740140fd7..027d5ec7314 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -664,6 +664,7 @@ AlterObjectNamespace_oid(Oid classId, Oid objid, Oid nspOid,
 
 		case OCLASS_CAST:
 		case OCLASS_CONSTRAINT:
+		case OCLASS_PERIOD:
 		case OCLASS_DEFAULT:
 		case OCLASS_LANGUAGE:
 		case OCLASS_LARGEOBJECT:
diff --git a/src/backend/commands/comment.c b/src/backend/commands/comment.c
index e9d50fc7d87..05fefb5b5ce 100644
--- a/src/backend/commands/comment.c
+++ b/src/backend/commands/comment.c
@@ -102,6 +102,16 @@ CommentObject(CommentStmt *stmt)
 								RelationGetRelationName(relation)),
 						 errdetail_relkind_not_supported(relation->rd_rel->relkind)));
 			break;
+
+		case OBJECT_PERIOD:
+			/* Periods can only go on tables */
+			if (relation->rd_rel->relkind != RELKIND_RELATION)
+				ereport(ERROR,
+						(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+						 errmsg("\"%s\" is not a table",
+								RelationGetRelationName(relation))));
+			break;
+
 		default:
 			break;
 	}
diff --git a/src/backend/commands/dropcmds.c b/src/backend/commands/dropcmds.c
index 85eec7e3947..3d7879f93c1 100644
--- a/src/backend/commands/dropcmds.c
+++ b/src/backend/commands/dropcmds.c
@@ -504,6 +504,7 @@ does_not_exist_skipping(ObjectType objtype, Node *object)
 		case OBJECT_DOMCONSTRAINT:
 		case OBJECT_LARGEOBJECT:
 		case OBJECT_PARAMETER_ACL:
+		case OBJECT_PERIOD:
 		case OBJECT_PUBLICATION_NAMESPACE:
 		case OBJECT_PUBLICATION_REL:
 		case OBJECT_TABCONSTRAINT:
diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c
index c95e9cf6f0e..c55434b62b1 100644
--- a/src/backend/commands/event_trigger.c
+++ b/src/backend/commands/event_trigger.c
@@ -1165,6 +1165,7 @@ EventTriggerSupportsObjectType(ObjectType obtype)
 		case OBJECT_OPCLASS:
 		case OBJECT_OPERATOR:
 		case OBJECT_OPFAMILY:
+		case OBJECT_PERIOD:
 		case OBJECT_POLICY:
 		case OBJECT_PROCEDURE:
 		case OBJECT_PUBLICATION:
@@ -1223,6 +1224,7 @@ EventTriggerSupportsObjectClass(ObjectClass objclass)
 		case OCLASS_CAST:
 		case OCLASS_COLLATION:
 		case OCLASS_CONSTRAINT:
+		case OCLASS_PERIOD:
 		case OCLASS_CONVERSION:
 		case OCLASS_DEFAULT:
 		case OCLASS_LANGUAGE:
@@ -2264,6 +2266,7 @@ stringify_grant_objtype(ObjectType objtype)
 		case OBJECT_OPCLASS:
 		case OBJECT_OPERATOR:
 		case OBJECT_OPFAMILY:
+		case OBJECT_PERIOD:
 		case OBJECT_POLICY:
 		case OBJECT_PUBLICATION:
 		case OBJECT_PUBLICATION_NAMESPACE:
@@ -2348,6 +2351,7 @@ stringify_adefprivs_objtype(ObjectType objtype)
 		case OBJECT_OPERATOR:
 		case OBJECT_OPFAMILY:
 		case OBJECT_PARAMETER_ACL:
+		case OBJECT_PERIOD:
 		case OBJECT_POLICY:
 		case OBJECT_PUBLICATION:
 		case OBJECT_PUBLICATION_NAMESPACE:
diff --git a/src/backend/commands/seclabel.c b/src/backend/commands/seclabel.c
index 5607273bf9f..af7177179ce 100644
--- a/src/backend/commands/seclabel.c
+++ b/src/backend/commands/seclabel.c
@@ -79,6 +79,7 @@ SecLabelSupportsObjectType(ObjectType objtype)
 		case OBJECT_OPERATOR:
 		case OBJECT_OPFAMILY:
 		case OBJECT_PARAMETER_ACL:
+		case OBJECT_PERIOD:
 		case OBJECT_POLICY:
 		case OBJECT_PUBLICATION_NAMESPACE:
 		case OBJECT_PUBLICATION_REL:
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 86e70bb4082..56d4eef568e 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -44,6 +44,7 @@
 #include "catalog/pg_largeobject.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_opclass.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_statistic_ext.h"
 #include "catalog/pg_tablespace.h"
 #include "catalog/pg_trigger.h"
@@ -150,6 +151,11 @@ typedef enum AlterTablePass
 	AT_PASS_OLD_INDEX,			/* re-add existing indexes */
 	AT_PASS_OLD_CONSTR,			/* re-add existing constraints */
 	/* We could support a RENAME COLUMN pass here, but not currently used */
+	/*
+	 * We must add PERIODs after columns, in case they reference a newly-added column,
+	 * and before constraints, in case a newly-added PK/FK references them.
+	 */
+	AT_PASS_ADD_PERIOD,			/* ADD PERIOD */
 	AT_PASS_ADD_CONSTR,			/* ADD constraints (initial examination) */
 	AT_PASS_COL_ATTRS,			/* set column attributes, eg NOT NULL */
 	AT_PASS_ADD_INDEXCONSTR,	/* ADD index-based constraints */
@@ -357,6 +363,7 @@ static void RangeVarCallbackForTruncate(const RangeVar *relation,
 static List *MergeAttributes(List *columns, const List *supers, char relpersistence,
 							 bool is_partition, List **supconstr,
 							 List **supnotnulls);
+static List *MergePeriods(char *relname, List *periods, List *tableElts, List *supers);
 static List *MergeCheckConstraint(List *constraints, const char *name, Node *expr);
 static void MergeChildAttribute(List *inh_columns, int exist_attno, int newcol_attno, const ColumnDef *newdef);
 static ColumnDef *MergeInheritedAttribute(List *inh_columns, int exist_attno, const ColumnDef *newdef);
@@ -437,6 +444,8 @@ static ObjectAddress ATExecAddColumn(List **wqueue, AlteredTableInfo *tab,
 									 AlterTableUtilityContext *context);
 static bool check_for_column_name_collision(Relation rel, const char *colname,
 											bool if_not_exists);
+static bool check_for_period_name_collision(Relation rel, const char *pername,
+											bool colexists, bool if_not_exists);
 static void add_column_datatype_dependency(Oid relid, int32 attnum, Oid typid);
 static void add_column_collation_dependency(Oid relid, int32 attnum, Oid collid);
 static ObjectAddress ATExecDropNotNull(Relation rel, const char *colName, bool recurse,
@@ -456,6 +465,12 @@ static ObjectAddress ATExecColumnDefault(Relation rel, const char *colName,
 										 Node *newDefault, LOCKMODE lockmode);
 static ObjectAddress ATExecCookedColumnDefault(Relation rel, AttrNumber attnum,
 											   Node *newDefault);
+static ObjectAddress ATExecAddPeriod(Relation rel, PeriodDef *period,
+									 AlterTableUtilityContext *context);
+static void ATExecDropPeriod(Relation rel, const char *periodName,
+							 DropBehavior behavior,
+							 bool recurse, bool recursing,
+							 bool missing_ok);
 static ObjectAddress ATExecAddIdentity(Relation rel, const char *colName,
 									   Node *def, LOCKMODE lockmode, bool recurse, bool recursing);
 static ObjectAddress ATExecSetIdentity(Relation rel, const char *colName,
@@ -663,6 +678,10 @@ static List *GetParentedForeignKeyRefs(Relation partition);
 static void ATDetachCheckNoForeignKeyRefs(Relation partition);
 static char GetAttributeCompression(Oid atttypid, const char *compression);
 static char GetAttributeStorage(Oid atttypid, const char *storagemode);
+static void AddRelationNewPeriod(Relation rel, PeriodDef *period);
+static void ValidatePeriod(Relation rel, PeriodDef *period);
+static Constraint *make_constraint_for_period(Relation rel, PeriodDef *period);
+static ColumnDef *make_range_column_for_period(PeriodDef *period);
 
 
 /* ----------------------------------------------------------------
@@ -891,6 +910,79 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 						stmt->partbound != NULL,
 						&old_constraints, &old_notnulls);
 
+	/*
+	 * Using the column list (including inherited columns),
+	 * find the start/end columns for each period.
+	 * PERIODs should be inherited too (but aren't yet).
+	 */
+	stmt->periods = MergePeriods(relname, stmt->periods, stmt->tableElts, inheritOids);
+
+	/*
+	 * For each PERIOD we need a GENERATED column.
+	 * Usually we must create this, so we add it to tableElts.
+	 * If the user says the column already exists,
+	 * make sure it is sensible.
+	 * These columns are not inherited,
+	 * so we don't worry about conflicts in tableElts.
+	 *
+	 * We allow this colexists option to support pg_upgrade,
+	 * so we have more control over the GENERATED column
+	 * (whose attnum must match the old value).
+	 */
+	foreach(listptr, stmt->periods)
+	{
+		PeriodDef *period = (PeriodDef *) lfirst(listptr);
+
+		if (period->colexists)
+		{
+			ListCell *cell;
+			bool found = false;
+
+			foreach(cell, stmt->tableElts)
+			{
+				ColumnDef  *colDef = lfirst(cell);
+
+				if (strcmp(period->periodname, colDef->colname) == 0)
+				{
+					/*
+					 * Lots to check here:
+					 * It must be GENERATED ALWAYS,
+					 * it must have the right expression,
+					 * it must be the right type,
+					 * it must be NOT NULL,
+					 * it must not be inherited.
+					 */
+					if (colDef->generated == '\0')
+						ereport(ERROR, (errmsg("Period %s uses a non-generated column", period->periodname)));
+
+					if (colDef->generated != ATTRIBUTE_GENERATED_STORED)
+						ereport(ERROR, (errmsg("Period %s uses a generated column that is not STORED", period->periodname)));
+
+					// TODO: check the GENERATED expression also.
+
+					if (!colDef->is_not_null && !IsBinaryUpgrade)
+						ereport(ERROR, (errmsg("Period %s uses a generated column that allows nulls", period->periodname)));
+
+					if (period->rngtypid != typenameTypeId(NULL, colDef->typeName))
+						ereport(ERROR, (errmsg("Period %s uses a generated column with the wrong type", period->periodname)));
+
+					if (!colDef->is_local)
+						ereport(ERROR, (errmsg("Period %s uses a generated column that is inherited", period->periodname)));
+
+					found = true;
+				}
+			}
+
+			if (!found)
+				ereport(ERROR, (errmsg("No column found with name %s", period->periodname)));
+		}
+		else
+		{
+			ColumnDef *col = make_range_column_for_period(period);
+			stmt->tableElts = lappend(stmt->tableElts, col);
+		}
+	}
+
 	/*
 	 * Create a tuple descriptor from the relation schema.  Note that this
 	 * deals with column names, types, and in-descriptor NOT NULL flags, but
@@ -1276,6 +1368,21 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 	foreach(listptr, nncols)
 		set_attnotnull(NULL, rel, lfirst_int(listptr), false, NoLock);
 
+	/*
+	 * Create periods for the table. This must come after we create columns
+	 * and before we create index constraints. It will automatically create
+	 * a CHECK constraint for the period.
+	 */
+	foreach(listptr, stmt->periods)
+	{
+		PeriodDef *period = (PeriodDef *) lfirst(listptr);
+
+		/* Don't update the count of check constraints twice */
+		CommandCounterIncrement();
+
+		AddRelationNewPeriod(rel, period);
+	}
+
 	ObjectAddressSet(address, RelationRelationId, relationId);
 
 	/*
@@ -1392,6 +1499,309 @@ BuildDescForRelation(const List *columns)
 	return desc;
 }
 
+/*
+ * make_constraint_for_period
+ *
+ * Builds a CHECK Constraint to ensure start < end.
+ * Returns the CHECK Constraint.
+ * Also fills in period->constraintname if needed.
+ */
+static Constraint *
+make_constraint_for_period(Relation rel, PeriodDef *period)
+{
+	ColumnRef  *scol, *ecol;
+	Constraint *constr;
+	TypeCacheEntry *type;
+
+	if (period->constraintname == NULL)
+		period->constraintname = ChooseConstraintName(RelationGetRelationName(rel),
+													  period->periodname,
+													  "check",
+													  RelationGetNamespace(rel),
+													  NIL);
+	scol = makeNode(ColumnRef);
+	scol->fields = list_make1(makeString(pstrdup(period->startcolname)));
+	scol->location = 0;
+
+	ecol = makeNode(ColumnRef);
+	ecol->fields = list_make1(makeString(pstrdup(period->endcolname)));
+	ecol->location = 0;
+
+	type = lookup_type_cache(period->coltypid, TYPECACHE_LT_OPR);
+	if (type->lt_opr == InvalidOid)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("column \"%s\" cannot be used in a PERIOD because its type %s has no less than operator",
+						period->startcolname, format_type_be(period->coltypid))));
+
+	constr = makeNode(Constraint);
+	constr->contype = CONSTR_CHECK;
+	constr->conname = period->constraintname;
+	constr->deferrable = false;
+	constr->initdeferred = false;
+	constr->location = -1;
+	constr->is_no_inherit = false;
+	constr->raw_expr = (Node *) makeSimpleA_Expr(AEXPR_OP,
+												 get_opname(type->lt_opr),
+												 (Node *) scol,
+												 (Node *) ecol,
+												 0);
+	constr->cooked_expr = NULL;
+	constr->skip_validation = false;
+	constr->initially_valid = true;
+
+	return constr;
+}
+
+/*
+ * make_range_column_for_period
+ *
+ * Builds a GENERATED ALWAYS range column based on the PERIOD
+ * start/end columns. Returns the ColumnDef.
+ */
+ColumnDef *
+make_range_column_for_period(PeriodDef *period)
+{
+	char *range_type_namespace;
+	char *range_type_name;
+	ColumnDef *col = makeNode(ColumnDef);
+	ColumnRef *startvar, *endvar;
+	Expr *rangeConstructor;
+
+	if (!get_typname_and_namespace(period->rngtypid, &range_type_name, &range_type_namespace))
+		elog(ERROR, "missing range type %d", period->rngtypid);
+
+	startvar = makeNode(ColumnRef);
+	startvar->fields = list_make1(makeString(pstrdup(period->startcolname)));
+	endvar = makeNode(ColumnRef);
+	endvar->fields = list_make1(makeString(pstrdup(period->endcolname)));
+	rangeConstructor = (Expr *) makeFuncCall(
+			list_make2(makeString(range_type_namespace), makeString(range_type_name)),
+			list_make2(startvar, endvar),
+			COERCE_EXPLICIT_CALL,
+			period->location);
+
+	col->colname = pstrdup(period->periodname);
+	col->typeName = makeTypeName(range_type_name);
+	col->compression = NULL;
+	col->inhcount = 0;
+	col->is_local = true;
+	col->is_not_null = true;
+	col->is_from_type = false;
+	col->storage = 0;
+	col->storage_name = NULL;
+	col->raw_default = (Node *) rangeConstructor;
+	col->cooked_default = NULL;
+	col->identity = 0;
+	col->generated = ATTRIBUTE_GENERATED_STORED;
+	col->collClause = NULL;
+	col->collOid = InvalidOid;
+	col->fdwoptions = NIL;
+	col->location = period->location;
+
+	return col;
+}
+
+/*
+ * ValidatePeriod
+ *
+ * Look up the attributes used by the PERIOD,
+ * make sure they exist, are not system columns,
+ * and have the same type and collation.
+ *
+ * You must have a RowExclusiveLock on pg_attribute
+ * before calling this function.
+ *
+ * Add our findings to these PeriodDef fields:
+ *
+ * coltypid - the type of PERIOD columns.
+ * startattnum - the attnum of the start column.
+ * endattnum - the attnum of the end column.
+ * rngtypid - the range type to use.
+ * rngattnum - the attnum of a pre-existing range column, or Invalid.
+ */
+static void
+ValidatePeriod(Relation rel, PeriodDef *period)
+{
+	HeapTuple starttuple;
+	HeapTuple endtuple;
+	Form_pg_attribute	atttuple;
+	Oid	attcollation;
+
+	/* Find the start column */
+	starttuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), period->startcolname);
+	if (!HeapTupleIsValid(starttuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						period->startcolname, RelationGetRelationName(rel))));
+	atttuple = (Form_pg_attribute) GETSTRUCT(starttuple);
+	period->coltypid = atttuple->atttypid;
+	attcollation = atttuple->attcollation;
+	period->startattnum = atttuple->attnum;
+
+	/* Make sure it's not a system column */
+	if (period->startattnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+				 errmsg("cannot use system column \"%s\" in period",
+						period->startcolname)));
+
+	/* Find the end column */
+	endtuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), period->endcolname);
+	if (!HeapTupleIsValid(endtuple))
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_COLUMN),
+				 errmsg("column \"%s\" of relation \"%s\" does not exist",
+						period->endcolname, RelationGetRelationName(rel))));
+	atttuple = (Form_pg_attribute) GETSTRUCT(endtuple);
+	period->endattnum = atttuple->attnum;
+
+	/* Make sure it's not a system column */
+	if (period->endattnum <= 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+				 errmsg("cannot use system column \"%s\" in period",
+						period->endcolname)));
+
+	/* Both columns must be of same type */
+	if (period->coltypid != atttuple->atttypid)
+		ereport(ERROR,
+				(errcode(ERRCODE_DATATYPE_MISMATCH),
+				 errmsg("start and end columns of period must be of same type")));
+
+	/* Both columns must have the same collation */
+	if (attcollation != atttuple->attcollation)
+		ereport(ERROR,
+				(errcode(ERRCODE_COLLATION_MISMATCH),
+				 errmsg("start and end columns of period must have same collation")));
+
+	/* Get the range type based on the start/end cols or the user's choice */
+	period->rngtypid = choose_rangetype_for_period(period);
+
+	/* If the GENERATED columns should already exist, make sure it is sensible. */
+	if (period->colexists)
+	{
+		HeapTuple rngtuple = SearchSysCacheCopyAttName(RelationGetRelid(rel), period->periodname);
+		if (!HeapTupleIsValid(rngtuple))
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+					 errmsg("column \"%s\" of relation \"%s\" does not exist",
+							period->periodname, RelationGetRelationName(rel))));
+		atttuple = (Form_pg_attribute) GETSTRUCT(rngtuple);
+
+		/*
+		 * Lots to check here:
+		 * It must be GENERATED ALWAYS,
+		 * it must have the right expression,
+		 * it must be the right type,
+		 * it must be NOT NULL,
+		 * it must not be inherited.
+		 */
+		if (atttuple->attgenerated == '\0')
+			ereport(ERROR, (errmsg("Period %s uses a non-generated column", period->periodname)));
+
+		if (atttuple->attgenerated != ATTRIBUTE_GENERATED_STORED)
+			ereport(ERROR, (errmsg("Period %s uses a generated column that is not STORED", period->periodname)));
+
+		// TODO: check the GENERATED expression also.
+
+		if (!atttuple->attnotnull && !IsBinaryUpgrade)
+			ereport(ERROR, (errmsg("Period %s uses a generated column that allows nulls", period->periodname)));
+
+		if (period->rngtypid != atttuple->atttypid)
+			ereport(ERROR, (errmsg("Period %s uses a generated column with the wrong type", period->periodname)));
+
+		if (!atttuple->attislocal)
+			ereport(ERROR, (errmsg("Period %s uses a generated column that is inherited", period->periodname)));
+
+		period->rngattnum = atttuple->attnum;
+
+		heap_freetuple(rngtuple);
+	}
+
+	heap_freetuple(starttuple);
+	heap_freetuple(endtuple);
+}
+
+/*
+ * choose_rangetype_for_period
+ *
+ * Find a suitable range type for operations involving this period.
+ * Use the rangetype option if provided, otherwise try to find a
+ * non-ambiguous existing type.
+ */
+Oid
+choose_rangetype_for_period(PeriodDef *period)
+{
+	Oid	rngtypid;
+
+	if (period->rangetypename != NULL)
+	{
+		/* Make sure it exists */
+		rngtypid = TypenameGetTypidExtended(period->rangetypename, false);
+		if (rngtypid == InvalidOid)
+			ereport(ERROR, (errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("Range type %s not found", period->rangetypename)));
+
+		/* Make sure it is a range type */
+		if (!type_is_range(rngtypid))
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("Type %s is not a range type", period->rangetypename)));
+
+		/* Make sure it matches the column type */
+		if (get_range_subtype(rngtypid) != period->coltypid)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("Range type %s does not match column type %s",
+						 period->rangetypename,
+						 format_type_be(period->coltypid))));
+	}
+	else
+	{
+		rngtypid = get_subtype_range(period->coltypid);
+		if (rngtypid == InvalidOid)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("no range type for %s found for period %s",
+							format_type_be(period->coltypid),
+							period->periodname),
+					 errhint("You can define a custom range type with CREATE TYPE")));
+
+	}
+
+	return rngtypid;
+}
+
+static void
+AddRelationNewPeriod(Relation rel, PeriodDef *period)
+{
+	Relation	attrelation;
+	Oid			conoid;
+	Constraint *constr;
+	List	   *newconstrs;
+
+	attrelation = table_open(AttributeRelationId, RowExclusiveLock);
+
+	/* Find the GENERATED range column */
+
+	period->rngattnum = get_attnum(RelationGetRelid(rel), period->periodname);
+	if (period->rngattnum == InvalidAttrNumber)
+		elog(ERROR, "missing attribute %s", period->periodname);
+
+	/* The parser has already found period->coltypid */
+
+	constr = make_constraint_for_period(rel, period);
+	newconstrs = AddRelationNewConstraints(rel, NIL, list_make1(constr), false, true, true, NULL);
+	conoid = ((CookedConstraint *) linitial(newconstrs))->conoid;
+
+	/* Save it */
+	StorePeriod(rel, period->periodname, period->startattnum, period->endattnum, period->rngattnum, conoid);
+
+	table_close(attrelation, RowExclusiveLock);
+}
+
 /*
  * Emit the right error or warning message for a "DROP" command issued on a
  * non-existent relation
@@ -3113,6 +3523,168 @@ MergeAttributes(List *columns, const List *supers, char relpersistence,
 }
 
 
+/*----------
+ * MergePeriods
+ *		Returns new period list given initial periods and superclasses.
+ *
+ * For now we don't support inheritence with PERIODs,
+ * but we might make it work eventually.
+ *
+ * We can omit lots of checks here and assume MergeAttributes already did them,
+ * for example that child & parents are not a mix of permanent and temp.
+ */
+static List *
+MergePeriods(char *relname, List *periods, List *tableElts, List *supers)
+{
+	ListCell   *entry;
+
+	/* If we have a PERIOD then supers must be empty. */
+
+	if (list_length(periods) > 0 && list_length(supers) > 0)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("Inheriting is not supported when a table has a PERIOD")));
+
+	/* If any parent table has a PERIOD, then fail. */
+
+	foreach(entry, supers)
+	{
+		Oid			parent = lfirst_oid(entry);
+		Relation	relation;
+		Relation	pg_period;
+		SysScanDesc scan;
+		ScanKeyData skey[1];
+		HeapTuple	tuple;
+
+		/* caller already got lock */
+		relation = table_open(parent, NoLock);
+		pg_period = table_open(PeriodRelationId, AccessShareLock);
+
+		ScanKeyInit(&skey[0],
+					Anum_pg_period_perrelid,
+					BTEqualStrategyNumber, F_OIDEQ,
+					ObjectIdGetDatum(parent));
+
+		scan = systable_beginscan(pg_period, PeriodRelidNameIndexId, true,
+								  NULL, 1, skey);
+
+		if (HeapTupleIsValid(tuple = systable_getnext(scan)))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("Inheriting from a table with a PERIOD is not supported")));
+
+		systable_endscan(scan);
+		table_close(pg_period, AccessShareLock);
+		table_close(relation, NoLock);
+	}
+
+	/*
+	 * Find the start & end columns and get their attno and type.
+	 * In the same pass, make sure the period doesn't conflict with any column names.
+	 * Also make sure the same period name isn't used more than once.
+	 */
+	foreach (entry, periods)
+	{
+		PeriodDef *period = lfirst(entry);
+		ListCell *entry2;
+		int i = 1;
+		Oid startcoltypid = InvalidOid;
+		Oid endcoltypid = InvalidOid;
+		Oid	startcolcollation = InvalidOid;
+		Oid	endcolcollation = InvalidOid;
+
+		period->startattnum = InvalidAttrNumber;
+		period->endattnum = InvalidAttrNumber;
+
+		if (SystemAttributeByName(period->periodname) != NULL)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_COLUMN),
+					 errmsg("period name \"%s\" conflicts with a system column name",
+							period->periodname)));
+
+		foreach (entry2, periods)
+		{
+			PeriodDef *period2 = lfirst(entry2);
+
+			if (period != period2 && strcmp(period->periodname, period2->periodname) == 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_DUPLICATE_OBJECT),
+						 errmsg("period name \"%s\" specified more than once",
+								period->periodname)));
+		}
+
+		foreach (entry2, tableElts)
+		{
+			ColumnDef *col = lfirst(entry2);
+			int32	atttypmod;
+			AclResult aclresult;
+
+			if (!period->colexists && strcmp(period->periodname, col->colname) == 0)
+				ereport(ERROR,
+						(errcode(ERRCODE_DUPLICATE_COLUMN),
+						 errmsg("period name \"%s\" conflicts with a column name",
+								period->periodname)));
+
+			if (strcmp(period->startcolname, col->colname) == 0)
+			{
+				period->startattnum = i;
+
+				typenameTypeIdAndMod(NULL, col->typeName, &startcoltypid, &atttypmod);
+
+				aclresult = object_aclcheck(TypeRelationId, startcoltypid, GetUserId(), ACL_USAGE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error_type(aclresult, startcoltypid);
+
+				startcolcollation = GetColumnDefCollation(NULL, col, startcoltypid);
+			}
+
+			if (strcmp(period->endcolname, col->colname) == 0)
+			{
+				period->endattnum = i;
+
+				typenameTypeIdAndMod(NULL, col->typeName, &endcoltypid, &atttypmod);
+
+				aclresult = object_aclcheck(TypeRelationId, endcoltypid, GetUserId(), ACL_USAGE);
+				if (aclresult != ACLCHECK_OK)
+					aclcheck_error_type(aclresult, endcoltypid);
+
+				endcolcollation = GetColumnDefCollation(NULL, col, endcoltypid);
+			}
+
+			i++;
+		}
+
+		/* Did we find the columns? */
+		if (period->startattnum == InvalidAttrNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+					 errmsg("column \"%s\" of relation \"%s\" does not exist",
+							period->startcolname, relname)));
+		if (period->endattnum == InvalidAttrNumber)
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_COLUMN),
+					 errmsg("column \"%s\" of relation \"%s\" does not exist",
+							period->endcolname, relname)));
+
+		/* Both columns must be of same type */
+		if (startcoltypid != endcoltypid)
+			ereport(ERROR,
+					(errcode(ERRCODE_DATATYPE_MISMATCH),
+					 errmsg("start and end columns of period must be of same type")));
+
+		/* Both columns must have the same collation */
+		if (startcolcollation != endcolcollation)
+			ereport(ERROR,
+					(errcode(ERRCODE_COLLATION_MISMATCH),
+					 errmsg("start and end columns of period must have same collation")));
+
+		period->coltypid = startcoltypid;
+		period->rngtypid = choose_rangetype_for_period(period);
+	}
+
+	return periods;
+}
+
 /*
  * MergeCheckConstraint
  *		Try to merge an inherited CHECK constraint with previous ones
@@ -4445,12 +5017,12 @@ AlterTable(AlterTableStmt *stmt, LOCKMODE lockmode,
  * existing query plans.  On the assumption it's not used for such, we
  * don't have to reject pending AFTER triggers, either.
  *
- * Also, since we don't have an AlterTableUtilityContext, this cannot be
+ * Also, if you don't pass an AlterTableUtilityContext, this cannot be
  * used for any subcommand types that require parse transformation or
  * could generate subcommands that have to be passed to ProcessUtility.
  */
 void
-AlterTableInternal(Oid relid, List *cmds, bool recurse)
+AlterTableInternal(Oid relid, List *cmds, bool recurse, AlterTableUtilityContext *context)
 {
 	Relation	rel;
 	LOCKMODE	lockmode = AlterTableGetLockLevel(cmds);
@@ -4459,7 +5031,7 @@ AlterTableInternal(Oid relid, List *cmds, bool recurse)
 
 	EventTriggerAlterTableRelid(relid);
 
-	ATController(NULL, rel, cmds, recurse, lockmode, NULL);
+	ATController(NULL, rel, cmds, recurse, lockmode, context);
 }
 
 /*
@@ -4552,6 +5124,8 @@ AlterTableGetLockLevel(List *cmds)
 			case AT_EnableReplicaRule:	/* may change SELECT rules */
 			case AT_EnableRule: /* may change SELECT rules */
 			case AT_DisableRule:	/* may change SELECT rules */
+			case AT_AddPeriod: /* shares namespace with columns, adds constraint */
+			case AT_DropPeriod:
 				cmd_lockmode = AccessExclusiveLock;
 				break;
 
@@ -4868,6 +5442,14 @@ ATPrepCmd(List **wqueue, Relation rel, AlterTableCmd *cmd,
 			/* This command never recurses */
 			pass = AT_PASS_ADD_OTHERCONSTR;
 			break;
+		case AT_AddPeriod: /* ALTER TABLE ... ADD PERIOD FOR name (start, end) */
+			ATSimplePermissions(cmd->subtype, rel, ATT_TABLE);
+			pass = AT_PASS_ADD_PERIOD;
+			break;
+		case AT_DropPeriod: /* ALTER TABLE ... DROP PERIOD FOR name */
+			ATSimplePermissions(cmd->subtype, rel, ATT_TABLE);
+			pass = AT_PASS_DROP;
+			break;
 		case AT_AddIdentity:
 			ATSimplePermissions(cmd->subtype, rel, ATT_TABLE | ATT_VIEW | ATT_FOREIGN_TABLE);
 			/* Set up recursion for phase 2; no other prep needed */
@@ -5275,6 +5857,14 @@ ATExecCmd(List **wqueue, AlteredTableInfo *tab,
 		case AT_CookedColumnDefault:	/* add a pre-cooked default */
 			address = ATExecCookedColumnDefault(rel, cmd->num, cmd->def);
 			break;
+		case AT_AddPeriod:
+			address = ATExecAddPeriod(rel, (PeriodDef *) cmd->def, context);
+			break;
+		case AT_DropPeriod:
+			ATExecDropPeriod(rel, cmd->name, cmd->behavior,
+								 false, false,
+								 cmd->missing_ok);
+			break;
 		case AT_AddIdentity:
 			cmd = ATParseTransformCmd(wqueue, tab, rel, cmd, false, lockmode,
 									  cur_pass, context);
@@ -6422,6 +7012,8 @@ alter_table_type_to_string(AlterTableType cmdtype)
 		case AT_AddColumn:
 		case AT_AddColumnToView:
 			return "ADD COLUMN";
+		case AT_AddPeriod:
+			return "ADD PERIOD";
 		case AT_ColumnDefault:
 		case AT_CookedColumnDefault:
 			return "ALTER COLUMN ... SET DEFAULT";
@@ -6447,6 +7039,8 @@ alter_table_type_to_string(AlterTableType cmdtype)
 			return "ALTER COLUMN ... SET COMPRESSION";
 		case AT_DropColumn:
 			return "DROP COLUMN";
+		case AT_DropPeriod:
+			return "DROP PERIOD";
 		case AT_AddIndex:
 		case AT_ReAddIndex:
 			return NULL;		/* not real grammar */
@@ -7420,14 +8014,29 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 /*
  * If a new or renamed column will collide with the name of an existing
  * column and if_not_exists is false then error out, else do nothing.
+ *
+ * See also check_for_period_name_collision.
  */
 static bool
 check_for_column_name_collision(Relation rel, const char *colname,
 								bool if_not_exists)
 {
-	HeapTuple	attTuple;
+	HeapTuple	attTuple, perTuple;
 	int			attnum;
 
+	/* If the name exists as a period, we're done. */
+	perTuple = SearchSysCache2(PERIODNAME,
+							   ObjectIdGetDatum(RelationGetRelid(rel)),
+							   PointerGetDatum(colname));
+	if (HeapTupleIsValid(perTuple))
+	{
+		ReleaseSysCache(perTuple);
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_COLUMN),
+				 errmsg("column name \"%s\" conflicts with a period name",
+						colname)));
+	}
+
 	/*
 	 * this test is deliberately not attisdropped-aware, since if one tries to
 	 * add a column matching a dropped column name, it's gonna fail anyway.
@@ -7471,6 +8080,77 @@ check_for_column_name_collision(Relation rel, const char *colname,
 	return true;
 }
 
+/*
+ * If a new period name will collide with the name of an existing column or
+ * period [and if_not_exists is false] then error out, else do nothing.
+ *
+ * See also check_for_column_name_collision.
+ */
+static bool
+check_for_period_name_collision(Relation rel, const char *pername,
+								bool colexists, bool if_not_exists)
+{
+	HeapTuple	attTuple, perTuple;
+	int			attnum;
+
+	/* TODO: implement IF [NOT] EXISTS for periods */
+	Assert(!if_not_exists);
+
+	/* If there is already a period with this name, then we're done. */
+	perTuple = SearchSysCache2(PERIODNAME,
+							   ObjectIdGetDatum(RelationGetRelid(rel)),
+							   PointerGetDatum(pername));
+	if (HeapTupleIsValid(perTuple))
+	{
+		if (if_not_exists)
+		{
+			ReleaseSysCache(perTuple);
+
+			ereport(NOTICE,
+					(errcode(ERRCODE_DUPLICATE_COLUMN),
+					 errmsg("period \"%s\" of relation \"%s\" already exists, skipping",
+							pername, RelationGetRelationName(rel))));
+			return false;
+		}
+
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_COLUMN),
+				 errmsg("period \"%s\" of relation \"%s\" already exists",
+						pername, RelationGetRelationName(rel))));
+	}
+
+	/*
+	 * this test is deliberately not attisdropped-aware, since if one tries to
+	 * add a column matching a dropped column name, it's gonna fail anyway.
+	 */
+	attTuple = SearchSysCache2(ATTNAME,
+							   ObjectIdGetDatum(RelationGetRelid(rel)),
+							   PointerGetDatum(pername));
+	if (HeapTupleIsValid(attTuple))
+	{
+		attnum = ((Form_pg_attribute) GETSTRUCT(attTuple))->attnum;
+		ReleaseSysCache(attTuple);
+
+		/*
+		 * We throw a different error message for conflicts with system column
+		 * names, since they are normally not shown and the user might otherwise
+		 * be confused about the reason for the conflict.
+		 */
+		if (attnum <= 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_COLUMN),
+					 errmsg("period name \"%s\" conflicts with a system column name",
+							pername)));
+		if (!colexists)
+			ereport(ERROR,
+					(errcode(ERRCODE_DUPLICATE_COLUMN),
+					 errmsg("period name \"%s\" conflicts with a column name",
+							pername)));
+	}
+
+	return true;
+}
+
 /*
  * Install a column's dependency on its datatype.
  */
@@ -8122,6 +8802,157 @@ ATExecCookedColumnDefault(Relation rel, AttrNumber attnum,
 	return address;
 }
 
+/*
+ * ALTER TABLE ADD PERIOD
+ *
+ * Return the address of the period.
+ */
+static ObjectAddress
+ATExecAddPeriod(Relation rel, PeriodDef *period, AlterTableUtilityContext *context)
+{
+	Relation		attrelation;
+	ObjectAddress	address = InvalidObjectAddress;
+	Constraint	   *constr;
+	ColumnDef	   *rangecol;
+	Oid				conoid, periodoid;
+	List		   *cmds = NIL;
+	AlterTableCmd  *cmd;
+
+	/*
+	 * PERIOD FOR SYSTEM_TIME is not yet implemented, but make sure no one uses
+	 * the name.
+	 */
+	if (strcmp(period->periodname, "system_time") == 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("PERIOD FOR SYSTEM_TIME is not supported")));
+
+	/* Parse options */
+	transformPeriodOptions(period);
+
+	/* The period name must not already exist */
+	(void) check_for_period_name_collision(rel, period->periodname, period->colexists, false);
+
+	attrelation = table_open(AttributeRelationId, RowExclusiveLock);
+	ValidatePeriod(rel, period);
+
+	/* Make the CHECK constraint */
+	constr = make_constraint_for_period(rel, period);
+	cmd = makeNode(AlterTableCmd);
+	cmd->subtype = AT_AddConstraint;
+	cmd->def = (Node *) constr;
+	cmds = lappend(cmds, cmd);
+	AlterTableInternal(RelationGetRelid(rel), cmds, true, context);
+	conoid = get_relation_constraint_oid(RelationGetRelid(rel), period->constraintname, false);
+
+	if (!period->colexists)
+	{
+		/* Make the range column */
+		rangecol = make_range_column_for_period(period);
+		cmd = makeNode(AlterTableCmd);
+		cmd->subtype = AT_AddColumn;
+		cmd->def = (Node *) rangecol;
+		cmd->name = period->periodname;
+		cmd->recurse = false; /* no, let the PERIOD recurse instead */
+		AlterTableInternal(RelationGetRelid(rel), list_make1(cmd), true, context);
+		period->rngattnum = get_attnum(RelationGetRelid(rel), period->periodname);
+		if (period->rngattnum == InvalidAttrNumber)
+			elog(ERROR, "missing attribute %s", period->periodname);
+
+	}
+
+	/* Save the Period */
+	periodoid = StorePeriod(rel, period->periodname, period->startattnum, period->endattnum, period->rngattnum, conoid);
+
+	ObjectAddressSet(address, PeriodRelationId, periodoid);
+
+	table_close(attrelation, RowExclusiveLock);
+
+	return address;
+}
+
+/*
+ * ALTER TABLE DROP PERIOD
+ *
+ * Like DROP COLUMN, we can't use the normal ALTER TABLE recursion mechanism.
+ */
+static void
+ATExecDropPeriod(Relation rel, const char *periodName,
+					 DropBehavior behavior,
+					 bool recurse, bool recursing,
+					 bool missing_ok)
+{
+	Relation	pg_period;
+	Form_pg_period period;
+	SysScanDesc scan;
+	ScanKeyData key;
+	HeapTuple	tuple;
+	bool		found = false;
+
+	/* At top level, permission check was done in ATPrepCmd, else do it */
+	if (recursing)
+		ATSimplePermissions(AT_DropPeriod, rel, ATT_TABLE);
+
+	pg_period = table_open(PeriodRelationId, RowExclusiveLock);
+
+	/*
+	 * Find and drop the target period
+	 */
+	ScanKeyInit(&key,
+				Anum_pg_period_perrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(RelationGetRelid(rel)));
+	scan = systable_beginscan(pg_period, PeriodRelidNameIndexId,
+							  true, NULL, 1, &key);
+
+	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+	{
+		ObjectAddress perobj;
+
+		period = (Form_pg_period) GETSTRUCT(tuple);
+
+		if (strcmp(NameStr(period->pername), periodName) != 0)
+			continue;
+
+		/*
+		 * Perform the actual period deletion
+		 */
+		perobj.classId = PeriodRelationId;
+		perobj.objectId = period->oid;
+		perobj.objectSubId = 0;
+
+		performDeletion(&perobj, behavior, 0);
+
+		found = true;
+
+		/* period found and dropped -- no need to keep looping */
+		break;
+	}
+
+	systable_endscan(scan);
+
+	if (!found)
+	{
+		if (!missing_ok)
+		{
+			ereport(ERROR,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("period \"%s\" on relation \"%s\" does not exist",
+							periodName, RelationGetRelationName(rel))));
+		}
+		else
+		{
+			ereport(NOTICE,
+					(errmsg("period \"%s\" on relation \"%s\" does not exist, skipping",
+							periodName, RelationGetRelationName(rel))));
+			table_close(pg_period, RowExclusiveLock);
+			return;
+		}
+	}
+
+	table_close(pg_period, RowExclusiveLock);
+}
+
 /*
  * ALTER TABLE ALTER COLUMN ADD IDENTITY
  *
@@ -9976,8 +10807,9 @@ ATAddForeignKeyConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
 	for (i = 0; i < numfks; i++)
 	{
 		char		attgenerated = TupleDescAttr(RelationGetDescr(rel), fkattnum[i] - 1)->attgenerated;
+		Bitmapset  *periods = get_period_attnos(RelationGetRelid(rel));
 
-		if (attgenerated)
+		if (attgenerated && !bms_is_member(fkattnum[i], periods))
 		{
 			/*
 			 * Check restrictions on UPDATE/DELETE actions, per SQL standard
@@ -14018,6 +14850,16 @@ RememberAllDependentForRebuilding(AlteredTableInfo *tab, AlterTableType subtype,
 				RememberConstraintForRebuilding(foundObject.objectId, tab);
 				break;
 
+			case OCLASS_PERIOD:
+				if (subtype == AT_AlterColumnType)
+					ereport(ERROR,
+							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+							 errmsg("cannot alter type of a column used by a period"),
+							 errdetail("%s depends on column \"%s\"",
+									   getObjectDescription(&foundObject, false),
+									   colName)));
+				break;
+
 			case OCLASS_REWRITE:
 				/* XXX someday see if we can cope with revising views */
 				if (subtype == AT_AlterColumnType)
@@ -14082,6 +14924,15 @@ RememberAllDependentForRebuilding(AlteredTableInfo *tab, AlterTableType subtype,
 					}
 					else
 					{
+						/*
+						 * If this GENERATED column is implementing a PERIOD,
+						 * keep going and we'll fail from the PERIOD instead.
+						 * This gives a more clear error message.
+						 */
+						Bitmapset *periodatts = get_period_attnos(RelationGetRelid(rel));
+						if (bms_is_member(col.objectSubId, periodatts))
+							break;
+
 						/*
 						 * This must be a reference from the expression of a
 						 * generated column elsewhere in the same table.
@@ -15896,7 +16747,7 @@ AlterTableMoveAll(AlterTableMoveAllStmt *stmt)
 
 		EventTriggerAlterTableStart((Node *) stmt);
 		/* OID is set by AlterTableInternal */
-		AlterTableInternal(lfirst_oid(l), cmds, false);
+		AlterTableInternal(lfirst_oid(l), cmds, false, NULL);
 		EventTriggerAlterTableEnd();
 	}
 
diff --git a/src/backend/commands/view.c b/src/backend/commands/view.c
index becc1fb4583..62c7b14f763 100644
--- a/src/backend/commands/view.c
+++ b/src/backend/commands/view.c
@@ -164,7 +164,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 			}
 
 			/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
-			AlterTableInternal(viewOid, atcmds, true);
+			AlterTableInternal(viewOid, atcmds, true, NULL);
 
 			/* Make the new view columns visible */
 			CommandCounterIncrement();
@@ -196,7 +196,7 @@ DefineVirtualRelation(RangeVar *relation, List *tlist, bool replace,
 		atcmds = list_make1(atcmd);
 
 		/* EventTriggerAlterTableStart called by ProcessUtilitySlow */
-		AlterTableInternal(viewOid, atcmds, true);
+		AlterTableInternal(viewOid, atcmds, true, NULL);
 
 		/*
 		 * There is very little to do here to update the view's dependencies.
diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 9533510affd..6ea5cb34f40 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -1347,8 +1347,46 @@ ExecForPortionOfLeftovers(ModifyTableContext *context,
 		}
 
 		/* store the new range */
-		leftoverSlot->tts_values[forPortionOf->rangeVar->varattno - 1] = leftover;
-		leftoverSlot->tts_isnull[forPortionOf->rangeVar->varattno - 1] = false;
+		if (forPortionOf->startVar)
+		{
+			/* For PERIODs we must split the range into start and end columns */
+
+			RangeType  *r = DatumGetRangeTypeP(leftover);
+			RangeBound	lower;
+			RangeBound	upper;
+			bool		empty;
+
+			range_deserialize(typcache, r, &lower, &upper, &empty);
+
+			if (lower.infinite)
+			{
+				leftoverSlot->tts_values[forPortionOf->startVar->varattno - 1] = 0;
+				leftoverSlot->tts_isnull[forPortionOf->startVar->varattno - 1] = true;
+			}
+			else
+			{
+				leftoverSlot->tts_values[forPortionOf->startVar->varattno - 1] = lower.val;
+				leftoverSlot->tts_isnull[forPortionOf->startVar->varattno - 1] = false;
+			}
+
+			if (upper.infinite)
+			{
+				leftoverSlot->tts_values[forPortionOf->endVar->varattno - 1] = 0;
+				leftoverSlot->tts_isnull[forPortionOf->endVar->varattno - 1] = true;
+			}
+			else
+			{
+				leftoverSlot->tts_values[forPortionOf->endVar->varattno - 1] = upper.val;
+				leftoverSlot->tts_isnull[forPortionOf->endVar->varattno - 1] = false;
+			}
+		}
+		else
+		{
+			/* Just store into the range/whatever column */
+
+			leftoverSlot->tts_values[forPortionOf->rangeVar->varattno - 1] = leftover;
+			leftoverSlot->tts_isnull[forPortionOf->rangeVar->varattno - 1] = false;
+		}
 		ExecMaterializeSlot(leftoverSlot);
 
 		/*
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index f78b59d4f17..3d6b5434492 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -1638,6 +1638,9 @@ exprLocation(const Node *expr)
 		case T_Constraint:
 			loc = ((const Constraint *) expr)->location;
 			break;
+		case T_PeriodDef:
+			loc = ((const PeriodDef *) expr)->location;
+			break;
 		case T_FunctionParameter:
 			/* just use typename's location */
 			loc = exprLocation((Node *) ((const FunctionParameter *) expr)->argType);
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index ed55a252197..2c2f3c858ce 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -28,6 +28,7 @@
 #include "access/stratnum.h"
 #include "access/sysattr.h"
 #include "catalog/pg_am.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_type.h"
 #include "commands/defrem.h"
@@ -1264,7 +1265,11 @@ transformForPortionOfClause(ParseState *pstate,
 	char *range_name = forPortionOf->range_name;
 	char *range_type_namespace = NULL;
 	char *range_type_name = NULL;
-	int range_attno = InvalidAttrNumber;
+	AttrNumber range_attno = InvalidAttrNumber;
+	AttrNumber start_attno = InvalidAttrNumber;
+	AttrNumber end_attno = InvalidAttrNumber;
+	char *startcolname = NULL;
+	char *endcolname = NULL;
 	Form_pg_attribute attr;
 	Oid	opclass;
 	Oid opfamily;
@@ -1308,6 +1313,53 @@ transformForPortionOfClause(ParseState *pstate,
 	if (!get_typname_and_namespace(attr->atttypid, &range_type_name, &range_type_namespace))
 		elog(ERROR, "cache lookup failed for type %u", attr->atttypid);
 
+	/*
+	 * If we are using a PERIOD, we need the start & end columns.
+	 * If the attribute it not a GENERATED column, we needn't query pg_period.
+	 */
+	if (attr->attgenerated == ATTRIBUTE_GENERATED_STORED)
+	{
+		HeapTuple perTuple = SearchSysCache2(PERIODNAME,
+											 ObjectIdGetDatum(RelationGetRelid(targetrel)),
+											 PointerGetDatum(range_name));
+		if (HeapTupleIsValid(perTuple))
+		{
+			Form_pg_period per = (Form_pg_period) GETSTRUCT(perTuple);
+			Form_pg_attribute perattr;
+
+			start_attno = per->perstart;
+			end_attno = per->perend;
+
+			perattr = TupleDescAttr(targetrel->rd_att, start_attno - 1);
+			startcolname = NameStr(perattr->attname);
+
+			result->startVar = makeVar(
+					rtindex,
+					start_attno,
+					perattr->atttypid,
+					perattr->atttypmod,
+					perattr->attcollation,
+					0);
+
+			perattr = TupleDescAttr(targetrel->rd_att, end_attno - 1);
+			endcolname = NameStr(perattr->attname);
+			result->endVar = makeVar(
+					rtindex,
+					end_attno,
+					perattr->atttypid,
+					perattr->atttypmod,
+					perattr->attcollation,
+					0);
+
+			ReleaseSysCache(perTuple);
+		}
+	}
+
+	if (start_attno == InvalidAttrNumber)
+	{
+		result->startVar = NULL;
+		result->endVar = NULL;
+	}
 
 	if (forPortionOf->target)
 		/*
@@ -1375,7 +1427,10 @@ transformForPortionOfClause(ParseState *pstate,
 	{
 		/*
 		 * Now make sure we update the start/end time of the record.
-		 * For a range col (r) this is `r = r * targetRange`.
+		 * For a range/etc col (r) this is `r = r * targetRange`.
+		 * For a PERIOD with cols (s, e) this is `s = lower(tsrange(s, e) * targetRange)`
+		 * and `e = upper(tsrange(s, e) * targetRange` (of course not necessarily with
+		 * tsrange, but with whatever range type is used there).
 		 */
 		Oid funcnamespace;
 		char *funcname;
@@ -1405,12 +1460,44 @@ transformForPortionOfClause(ParseState *pstate,
 				list_make2(copyObject(rangeVar), targetExpr),
 				COERCE_EXPLICIT_CALL,
 				forPortionOf->location);
-		rangeTLEExpr = (Expr *) transformExpr(pstate, (Node *) rangeTLEExpr, EXPR_KIND_UPDATE_PORTION);
 
-		/* Make a TLE to set the range column */
+		/* Make a TLE to set the range column or start/end columns */
 		result->rangeTargetList = NIL;
-		tle = makeTargetEntry(rangeTLEExpr, range_attno, range_name, false);
-		result->rangeTargetList = lappend(result->rangeTargetList, tle);
+
+		if (result->startVar)
+		{
+			Expr *boundTLEExpr;
+
+			/* set the start column */
+			boundTLEExpr = (Expr *) makeFuncCall(SystemFuncName("lower"),
+					list_make1(rangeTLEExpr),
+					COERCE_EXPLICIT_CALL,
+					forPortionOf->location);
+			boundTLEExpr = (Expr *) transformExpr(pstate, (Node *) boundTLEExpr, EXPR_KIND_UPDATE_PORTION);
+			tle = makeTargetEntry(boundTLEExpr, start_attno, startcolname, false);
+			result->rangeTargetList = lappend(result->rangeTargetList, tle);
+
+			/* set the end column */
+			boundTLEExpr = (Expr *) makeFuncCall(SystemFuncName("upper"),
+					list_make1(rangeTLEExpr),
+					COERCE_EXPLICIT_CALL,
+					forPortionOf->location);
+			boundTLEExpr = (Expr *) transformExpr(pstate, (Node *) boundTLEExpr, EXPR_KIND_UPDATE_PORTION);
+			tle = makeTargetEntry(boundTLEExpr, end_attno, endcolname, false);
+			result->rangeTargetList = lappend(result->rangeTargetList, tle);
+
+			/* Mark the start/end columns as requiring update permissions */
+			target_perminfo->updatedCols = bms_add_member(target_perminfo->updatedCols,
+														  start_attno - FirstLowInvalidHeapAttributeNumber);
+			target_perminfo->updatedCols = bms_add_member(target_perminfo->updatedCols,
+														  end_attno - FirstLowInvalidHeapAttributeNumber);
+		}
+		else
+		{
+			rangeTLEExpr = (Expr *) transformExpr(pstate, (Node *) rangeTLEExpr, EXPR_KIND_UPDATE_PORTION);
+			tle = makeTargetEntry(rangeTLEExpr, range_attno, range_name, false);
+			result->rangeTargetList = lappend(result->rangeTargetList, tle);
+		}
 
 		/* Mark the range column as requiring update permissions */
 		target_perminfo->updatedCols = bms_add_member(target_perminfo->updatedCols,
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 4bbaf992bb0..88c8c157c92 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -596,7 +596,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <keyword> col_name_keyword reserved_keyword
 %type <keyword> bare_label_keyword
 
-%type <node>	TableConstraint TableLikeClause
+%type <node>	TableConstraint TableLikeClause TablePeriod
 %type <ival>	TableLikeOptionList TableLikeOption
 %type <str>		column_compression opt_column_compression column_storage opt_column_storage
 %type <list>	ColQualList
@@ -2626,6 +2626,24 @@ alter_table_cmd:
 					n->def = (Node *) $4;
 					$$ = (Node *) n;
 				}
+			/* ALTER TABLE <name> ADD PERIOD FOR <name> (<name>, <name>) */
+			| ADD_P TablePeriod
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_AddPeriod;
+					n->def = $2;
+					$$ = (Node *)n;
+				}
+			/* ALTER TABLE <name> DROP PERIOD FOR <name> [RESTRICT|CASCADE] */
+			| DROP PERIOD FOR name opt_drop_behavior
+				{
+					AlterTableCmd *n = makeNode(AlterTableCmd);
+					n->subtype = AT_DropPeriod;
+					n->name = $4;
+					n->behavior = $5;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			/* ALTER TABLE <name> ADD CONSTRAINT ... */
 			| ADD_P TableConstraint
 				{
@@ -3755,8 +3773,10 @@ TableElement:
 			columnDef							{ $$ = $1; }
 			| TableLikeClause					{ $$ = $1; }
 			| TableConstraint					{ $$ = $1; }
+			| TablePeriod						{ $$ = $1; }
 		;
 
+
 TypedTableElement:
 			columnOptions						{ $$ = $1; }
 			| TableConstraint					{ $$ = $1; }
@@ -4108,6 +4128,19 @@ TableLikeOption:
 		;
 
 
+TablePeriod:
+			PERIOD FOR name '(' name ',' name ')' opt_definition
+				{
+					PeriodDef *n = makeNode(PeriodDef);
+					n->periodname = $3;
+					n->startcolname = $5;
+					n->endcolname = $7;
+					n->options = $9;
+					n->location = @1;
+					$$ = (Node *) n;
+				}
+		;
+
 /* ConstraintElem specifies constraint syntax which is not embedded into
  *	a column definition. ColConstraintElem specifies the embedded form.
  * - thomas 1997-12-03
@@ -7174,6 +7207,14 @@ CommentStmt:
 					n->comment = $9;
 					$$ = (Node *) n;
 				}
+			| COMMENT ON PERIOD any_name IS comment_text
+				{
+					CommentStmt *n = makeNode(CommentStmt);
+					n->objtype = OBJECT_PERIOD;
+					n->object = (Node *) $4;
+					n->comment = $6;
+					$$ = (Node *) n;
+				}
 			| COMMENT ON LARGE_P OBJECT_P NumericOnly IS comment_text
 				{
 					CommentStmt *n = makeNode(CommentStmt);
@@ -17391,7 +17432,6 @@ unreserved_keyword:
 			| PARTITION
 			| PASSING
 			| PASSWORD
-			| PERIOD
 			| PLANS
 			| POLICY
 			| PORTION
@@ -17685,6 +17725,7 @@ reserved_keyword:
 			| ONLY
 			| OR
 			| ORDER
+			| PERIOD
 			| PLACING
 			| PRIMARY
 			| REFERENCES
diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index 6f5d9e26925..a4b2e63f05b 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -22,6 +22,7 @@
 #include "access/table.h"
 #include "catalog/heap.h"
 #include "catalog/namespace.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "nodes/makefuncs.h"
@@ -3182,6 +3183,7 @@ expandNSItemAttrs(ParseState *pstate, ParseNamespaceItem *nsitem,
 				  int sublevels_up, bool require_col_privs, int location)
 {
 	RangeTblEntry *rte = nsitem->p_rte;
+	Bitmapset  *periodatts = NULL;
 	RTEPermissionInfo *perminfo = nsitem->p_perminfo;
 	List	   *names,
 			   *vars;
@@ -3205,12 +3207,20 @@ expandNSItemAttrs(ParseState *pstate, ParseNamespaceItem *nsitem,
 		perminfo->requiredPerms |= ACL_SELECT;
 	}
 
+	/* Get PERIOD columns to exclude */
+	if (rte->rtekind == RTE_RELATION)
+		periodatts = get_period_attnos(rte->relid);
+
 	forboth(name, names, var, vars)
 	{
 		char	   *label = strVal(lfirst(name));
 		Var		   *varnode = (Var *) lfirst(var);
 		TargetEntry *te;
 
+		/* If this column is from a PERIOD, skip it */
+		if (bms_is_member(varnode->varattno, periodatts))
+				continue;
+
 		te = makeTargetEntry((Expr *) varnode,
 							 (AttrNumber) pstate->p_next_resno++,
 							 label,
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index c7efd8d8cee..d36c3b82777 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -37,6 +37,7 @@
 #include "catalog/pg_constraint.h"
 #include "catalog/pg_opclass.h"
 #include "catalog/pg_operator.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_statistic_ext.h"
 #include "catalog/pg_type.h"
 #include "commands/comment.h"
@@ -80,6 +81,7 @@ typedef struct
 	bool		isforeign;		/* true if CREATE/ALTER FOREIGN TABLE */
 	bool		isalter;		/* true if altering existing table */
 	List	   *columns;		/* ColumnDef items */
+	List	   *periods;		/* PeriodDef items */
 	List	   *ckconstraints;	/* CHECK constraints */
 	List	   *nnconstraints;	/* NOT NULL constraints */
 	List	   *fkconstraints;	/* FOREIGN KEY constraints */
@@ -111,6 +113,8 @@ typedef struct
 
 static void transformColumnDefinition(CreateStmtContext *cxt,
 									  ColumnDef *column);
+static void transformTablePeriod(CreateStmtContext *cxt,
+								 PeriodDef *period);
 static void transformTableConstraint(CreateStmtContext *cxt,
 									 Constraint *constraint);
 static void transformTableLikeClause(CreateStmtContext *cxt,
@@ -240,6 +244,7 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	cxt.inhRelations = stmt->inhRelations;
 	cxt.isalter = false;
 	cxt.columns = NIL;
+	cxt.periods = NIL;
 	cxt.ckconstraints = NIL;
 	cxt.nnconstraints = NIL;
 	cxt.fkconstraints = NIL;
@@ -280,6 +285,10 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 				transformColumnDefinition(&cxt, (ColumnDef *) element);
 				break;
 
+			case T_PeriodDef:
+				transformTablePeriod(&cxt, (PeriodDef *) element);
+				break;
+
 			case T_Constraint:
 				transformTableConstraint(&cxt, (Constraint *) element);
 				break;
@@ -347,6 +356,7 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	 * Output results.
 	 */
 	stmt->tableElts = cxt.columns;
+	stmt->periods = cxt.periods;
 	stmt->constraints = cxt.ckconstraints;
 	stmt->nnconstraints = cxt.nnconstraints;
 
@@ -922,6 +932,91 @@ transformColumnDefinition(CreateStmtContext *cxt, ColumnDef *column)
 	}
 }
 
+void
+transformPeriodOptions(PeriodDef *period)
+{
+	ListCell   *option;
+	DefElem	   *dconstraintname = NULL;
+	DefElem	   *drangetypename = NULL;
+	DefElem	   *dcolexists = NULL;
+
+	foreach(option, period->options)
+	{
+		DefElem    *defel = (DefElem *) lfirst(option);
+
+		if (strcmp(defel->defname, "check_constraint_name") == 0)
+		{
+			if (dconstraintname)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			dconstraintname = defel;
+		}
+		else if (strcmp(defel->defname, "rangetype") == 0)
+		{
+			if (drangetypename)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			drangetypename = defel;
+		}
+		else if (strcmp(defel->defname, "colexists") == 0)
+		{
+			if (dcolexists)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("conflicting or redundant options")));
+			dcolexists = defel;
+		}
+		else
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("option \"%s\" not recognized", defel->defname)));
+	}
+
+	if (dconstraintname != NULL)
+		period->constraintname = defGetString(dconstraintname);
+	else
+		period->constraintname = NULL;
+
+	if (drangetypename != NULL)
+		period->rangetypename = defGetString(drangetypename);
+	else
+		period->rangetypename = NULL;
+
+	if (dcolexists != NULL)
+		period->colexists = defGetBoolean(dcolexists);
+	else
+		period->colexists = false;
+}
+
+/*
+ * transformTablePeriod
+ *		transform a PeriodDef node within CREATE TABLE
+ */
+static void
+transformTablePeriod(CreateStmtContext *cxt, PeriodDef *period)
+{
+	if (strcmp(period->periodname, "system_time") == 0)
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("PERIOD FOR SYSTEM_TIME is not supported"),
+					 parser_errposition(cxt->pstate,
+										period->location)));
+
+	if (strcmp(period->startcolname, period->endcolname) == 0)
+		ereport(ERROR, (errmsg("column \"%s\" can't be the start and end column for period \"%s\"",
+						period->startcolname, period->periodname)));
+
+	/*
+	 * Determine the column info and range type so that transformIndexConstraints
+	 * knows how to create PRIMARY KEY/UNIQUE constraints using this PERIOD.
+	 */
+	transformPeriodOptions(period);
+
+	cxt->periods = lappend(cxt->periods, period);
+}
+
 /*
  * transformTableConstraint
  *		transform a Constraint node within CREATE TABLE or ALTER TABLE
@@ -1012,6 +1107,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 	AttrNumber	parent_attno;
 	Relation	relation;
 	TupleDesc	tupleDesc;
+	Bitmapset  *periodatts;
 	AclResult	aclresult;
 	char	   *comment;
 	ParseCallbackState pcbstate;
@@ -1064,6 +1160,7 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 	}
 
 	tupleDesc = RelationGetDescr(relation);
+	periodatts = get_period_attnos(RelationGetRelid(relation));
 
 	/*
 	 * Insert the copied attributes into the cxt for the new table definition.
@@ -1073,10 +1170,18 @@ transformTableLikeClause(CreateStmtContext *cxt, TableLikeClause *table_like_cla
 	for (parent_attno = 1; parent_attno <= tupleDesc->natts;
 		 parent_attno++)
 	{
-		Form_pg_attribute attribute = TupleDescAttr(tupleDesc,
-													parent_attno - 1);
+		Form_pg_attribute attribute;
 		ColumnDef  *def;
 
+		/*
+		 * If this column is from a PERIOD, skip it
+		 * (since LIKE never copies PERIODs).
+		 */
+		if (bms_is_member(parent_attno, periodatts))
+			continue;
+
+		attribute = TupleDescAttr(tupleDesc, parent_attno - 1);
+
 		/*
 		 * Ignore dropped columns in the parent.
 		 */
@@ -2573,6 +2678,7 @@ transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
 					break;
 				}
 			}
+
 			if (found)
 			{
 				/*
@@ -2589,6 +2695,22 @@ transformIndexConstraint(Constraint *constraint, CreateStmtContext *cxt)
 					column->is_not_null = true;
 				}
 			}
+			else if (constraint->without_overlaps &&
+					 lc == list_last_cell(constraint->keys))
+			{
+				/* If the key is WITHOUT OVERLAPS, a PERIOD will work too. */
+				PeriodDef  *period = NULL;
+
+				foreach(columns, cxt->periods)
+				{
+					period = lfirst_node(PeriodDef, columns);
+					if (strcmp(period->periodname, key) == 0)
+					{
+						found = true;
+						break;
+					}
+				}
+			}
 			else if (SystemAttributeByName(key) != NULL)
 			{
 				/*
@@ -3017,6 +3139,10 @@ transformIndexStmt(Oid relid, IndexStmt *stmt, const char *queryString)
 		}
 	}
 
+	/* take care of the period */
+	if (stmt->period)
+		stmt->period->oid = get_period_oid(relid, stmt->period->periodname, false);
+
 	/*
 	 * Check that only the base rel is mentioned.  (This should be dead code
 	 * now that add_missing_from is history.)
@@ -3474,6 +3600,7 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 	cxt.inhRelations = NIL;
 	cxt.isalter = true;
 	cxt.columns = NIL;
+	cxt.periods = NIL;
 	cxt.ckconstraints = NIL;
 	cxt.nnconstraints = NIL;
 	cxt.fkconstraints = NIL;
@@ -3536,6 +3663,22 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 						 (int) nodeTag(cmd->def));
 				break;
 
+			case AT_AddPeriod:
+				{
+					/*
+					 * We can't call transformTablePeriod here
+					 * because it looks at cxt->columns
+					 * and in an ALTER statement the columns might already exists
+					 * (or not).
+					 */
+					// TODO: it doesn't look at cxt->columns any more.
+					// So should we call it here? To do what?
+					// Well it might be useful to know about it in cxt->periods at least.
+					transformTablePeriod(&cxt, castNode(PeriodDef, cmd->def));
+					newcmds = lappend(newcmds, cmd);
+					break;
+				}
+
 			case AT_AlterColumnType:
 				{
 					ColumnDef  *def = castNode(ColumnDef, cmd->def);
diff --git a/src/backend/utils/adt/Makefile b/src/backend/utils/adt/Makefile
index 199eae525d1..d04c75b3980 100644
--- a/src/backend/utils/adt/Makefile
+++ b/src/backend/utils/adt/Makefile
@@ -78,6 +78,7 @@ OBJS = \
 	oracle_compat.o \
 	orderedsetaggs.o \
 	partitionfuncs.o \
+	period.o \
 	pg_locale.o \
 	pg_lsn.o \
 	pg_upgrade_support.o \
diff --git a/src/backend/utils/adt/period.c b/src/backend/utils/adt/period.c
new file mode 100644
index 00000000000..0ed4304e16d
--- /dev/null
+++ b/src/backend/utils/adt/period.c
@@ -0,0 +1,56 @@
+/*-------------------------------------------------------------------------
+ *
+ * period.c
+ *	  Functions to support periods.
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/backend/utils/adt/period.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "executor/tuptable.h"
+#include "fmgr.h"
+#include "nodes/primnodes.h"
+#include "utils/fmgrprotos.h"
+#include "utils/period.h"
+#include "utils/rangetypes.h"
+
+Datum period_to_range(TupleTableSlot *slot, int startattno, int endattno, Oid rangetype)
+{
+	Datum startvalue;
+	Datum endvalue;
+	Datum result;
+	bool	startisnull;
+	bool	endisnull;
+	LOCAL_FCINFO(fcinfo, 2);
+	FmgrInfo	flinfo;
+	FuncExpr   *f;
+
+	InitFunctionCallInfoData(*fcinfo, &flinfo, 2, InvalidOid, NULL, NULL);
+	f = makeNode(FuncExpr);
+	f->funcresulttype = rangetype;
+	flinfo.fn_expr = (Node *) f;
+	flinfo.fn_extra = NULL;
+
+	/* compute oldvalue */
+	startvalue = slot_getattr(slot, startattno, &startisnull);
+	endvalue = slot_getattr(slot, endattno, &endisnull);
+
+	fcinfo->args[0].value = startvalue;
+	fcinfo->args[0].isnull = startisnull;
+	fcinfo->args[1].value = endvalue;
+	fcinfo->args[1].isnull = endisnull;
+
+	result = range_constructor2(fcinfo);
+	if (fcinfo->isnull)
+		elog(ERROR, "function %u returned NULL", flinfo.fn_oid);
+
+	return result;
+}
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index e9a3c146d11..f070a9fa796 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -31,6 +31,7 @@
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_opclass.h"
 #include "catalog/pg_operator.h"
+#include "catalog/pg_period.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_publication.h"
 #include "catalog/pg_range.h"
@@ -995,6 +996,68 @@ get_attoptions(Oid relid, int16 attnum)
 	return result;
 }
 
+/*				---------- PG_PERIOD CACHE ----------				 */
+
+/*
+ * get_periodname - given its OID, look up a period
+ *
+ * If missing_ok is false, throw an error if the period is not found.
+ * If true, just return InvalidOid.
+ */
+char *
+get_periodname(Oid periodid, bool missing_ok)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache1(PERIODOID,
+						 ObjectIdGetDatum(periodid));
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_period period_tup = (Form_pg_period) GETSTRUCT(tp);
+		char	   *result;
+
+		result = pstrdup(NameStr(period_tup->pername));
+		ReleaseSysCache(tp);
+		return result;
+	}
+
+	if (!missing_ok)
+		elog(ERROR, "cache lookup failed for period %d",
+			 periodid);
+	return NULL;
+}
+
+/*
+ * get_period_oid - gets its relation and name, look up a period
+ *
+ * If missing_ok is false, throw an error if the cast is not found.  If
+ * true, just return InvalidOid.
+ */
+Oid
+get_period_oid(Oid relid, const char *periodname, bool missing_ok)
+{
+	HeapTuple	tp;
+
+	tp = SearchSysCache2(PERIODNAME,
+						 ObjectIdGetDatum(relid),
+						 PointerGetDatum(periodname));
+
+	if (HeapTupleIsValid(tp))
+	{
+		Form_pg_period period_tup = (Form_pg_period) GETSTRUCT(tp);
+		Oid result;
+
+		result = period_tup->oid;
+		ReleaseSysCache(tp);
+		return result;
+	}
+
+	if (!missing_ok)
+		elog(ERROR, "cache lookup failed for period %s",
+			 periodname);
+	return InvalidOid;
+}
+
 /*				---------- PG_CAST CACHE ----------					 */
 
 /*
@@ -3509,6 +3572,30 @@ get_multirange_range(Oid multirangeOid)
 		return InvalidOid;
 }
 
+Oid
+get_subtype_range(Oid subtypeOid)
+{
+	CatCList *catlist;
+	Oid	result = InvalidOid;
+
+	catlist = SearchSysCacheList1(RANGESUBTYPE, ObjectIdGetDatum(subtypeOid));
+
+	if (catlist->n_members == 1)
+	{
+		HeapTuple	tuple = &catlist->members[0]->tuple;
+		Form_pg_range rngtup = (Form_pg_range) GETSTRUCT(tuple);
+		result = rngtup->rngtypid;
+		ReleaseCatCacheList(catlist);
+	}
+	else if (catlist->n_members > 1)
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_DATATYPE),
+				 errmsg("ambiguous range for type %s",
+						format_type_be(subtypeOid))));
+
+	return result;
+}
+
 /*				---------- PG_INDEX CACHE ----------				 */
 
 /*
diff --git a/src/bin/pg_dump/pg_backup_archiver.c b/src/bin/pg_dump/pg_backup_archiver.c
index d97ebaff5b8..0e8355d659e 100644
--- a/src/bin/pg_dump/pg_backup_archiver.c
+++ b/src/bin/pg_dump/pg_backup_archiver.c
@@ -3519,6 +3519,7 @@ _getObjectDescription(PQExpBuffer buf, const TocEntry *te)
 			 strcmp(type, "DATABASE PROPERTIES") == 0 ||
 			 strcmp(type, "DEFAULT") == 0 ||
 			 strcmp(type, "FK CONSTRAINT") == 0 ||
+			 strcmp(type, "PERIOD") == 0 ||
 			 strcmp(type, "INDEX") == 0 ||
 			 strcmp(type, "RULE") == 0 ||
 			 strcmp(type, "TRIGGER") == 0 ||
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 171e5916965..bb8a8ce1633 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -6628,6 +6628,7 @@ getTables(Archive *fout, int *numTables)
 	int			i_reltype;
 	int			i_relowner;
 	int			i_relchecks;
+	int			i_nperiod;
 	int			i_relhasindex;
 	int			i_relhasrules;
 	int			i_relpages;
@@ -6705,6 +6706,14 @@ getTables(Archive *fout, int *numTables)
 		appendPQExpBufferStr(query,
 							 "c.relhasoids, ");
 
+	/* In PG17 upwards we have PERIODs. */
+	if (fout->remoteVersion >= 170000)
+		appendPQExpBufferStr(query,
+							 "(SELECT count(*) FROM pg_period WHERE perrelid = c.oid) AS nperiods, ");
+	else
+		appendPQExpBufferStr(query,
+							 "0 AS nperiods, ");
+
 	if (fout->remoteVersion >= 90300)
 		appendPQExpBufferStr(query,
 							 "c.relispopulated, ");
@@ -6842,6 +6851,7 @@ getTables(Archive *fout, int *numTables)
 	i_reltype = PQfnumber(res, "reltype");
 	i_relowner = PQfnumber(res, "relowner");
 	i_relchecks = PQfnumber(res, "relchecks");
+	i_nperiod = PQfnumber(res, "nperiods");
 	i_relhasindex = PQfnumber(res, "relhasindex");
 	i_relhasrules = PQfnumber(res, "relhasrules");
 	i_relpages = PQfnumber(res, "relpages");
@@ -6925,6 +6935,7 @@ getTables(Archive *fout, int *numTables)
 		}
 		tblinfo[i].reltablespace = pg_strdup(PQgetvalue(res, i, i_reltablespace));
 		tblinfo[i].hasoids = (strcmp(PQgetvalue(res, i, i_relhasoids), "t") == 0);
+		tblinfo[i].nperiod = atoi(PQgetvalue(res, i, i_nperiod));
 		tblinfo[i].hastriggers = (strcmp(PQgetvalue(res, i, i_relhastriggers), "t") == 0);
 		tblinfo[i].relpersistence = *(PQgetvalue(res, i, i_relpersistence));
 		tblinfo[i].relispopulated = (strcmp(PQgetvalue(res, i, i_relispopulated), "t") == 0);
@@ -8589,7 +8600,7 @@ getTransforms(Archive *fout, int *numTransforms)
 /*
  * getTableAttrs -
  *	  for each interesting table, read info about its attributes
- *	  (names, types, default values, CHECK constraints, etc)
+ *	  (names, types, default values, CHECK constraints, PERIODs, etc)
  *
  *	modifies tblinfo
  */
@@ -8642,6 +8653,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 	for (int i = 0; i < numTables; i++)
 	{
 		TableInfo  *tbinfo = &tblinfo[i];
+		int			ndumpablechecks;	/* number of CHECK constraints that do
+										   not belong to a period */
 
 		/* Don't bother to collect info for sequences */
 		if (tbinfo->relkind == RELKIND_SEQUENCE)
@@ -8656,7 +8669,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			appendPQExpBufferChar(tbloids, ',');
 		appendPQExpBuffer(tbloids, "%u", tbinfo->dobj.catId.oid);
 
-		if (tbinfo->ncheck > 0)
+		ndumpablechecks = tbinfo->ncheck - tbinfo->nperiod;
+		if (ndumpablechecks > 0)
 		{
 			/* Also make a list of the ones with check constraints */
 			if (checkoids->len > 1) /* do we have more than the '{'? */
@@ -9195,15 +9209,36 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		pg_log_info("finding table check constraints");
 
 		resetPQExpBuffer(q);
-		appendPQExpBuffer(q,
-						  "SELECT c.tableoid, c.oid, conrelid, conname, "
-						  "pg_catalog.pg_get_constraintdef(c.oid) AS consrc, "
-						  "conislocal, convalidated "
-						  "FROM unnest('%s'::pg_catalog.oid[]) AS src(tbloid)\n"
-						  "JOIN pg_catalog.pg_constraint c ON (src.tbloid = c.conrelid)\n"
-						  "WHERE contype = 'c' "
-						  "ORDER BY c.conrelid, c.conname",
-						  checkoids->data);
+		if (fout->remoteVersion >= 170000)
+		{
+			/*
+			 * PERIODs were added in v17 and we don't dump CHECK
+			 * constraints for them.
+			 */
+			appendPQExpBuffer(q,
+							  "SELECT c.tableoid, c.oid, conrelid, conname, "
+							  "pg_catalog.pg_get_constraintdef(c.oid) AS consrc, "
+							  "conislocal, convalidated "
+							  "FROM unnest('%s'::pg_catalog.oid[]) AS src(tbloid)\n"
+							  "JOIN pg_catalog.pg_constraint c ON (src.tbloid = c.conrelid)\n"
+							  "WHERE contype = 'c' "
+							  "   AND NOT EXISTS (SELECT FROM pg_period "
+							  "                   WHERE (perrelid, perconstraint) = (conrelid, c.oid)) "
+							  "ORDER BY c.conrelid, c.conname",
+							  checkoids->data);
+		}
+		else
+		{
+			appendPQExpBuffer(q,
+							  "SELECT c.tableoid, c.oid, conrelid, conname, "
+							  "pg_catalog.pg_get_constraintdef(c.oid) AS consrc, "
+							  "conislocal, convalidated "
+							  "FROM unnest('%s'::pg_catalog.oid[]) AS src(tbloid)\n"
+							  "JOIN pg_catalog.pg_constraint c ON (src.tbloid = c.conrelid)\n"
+							  "WHERE contype = 'c' "
+							  "ORDER BY c.conrelid, c.conname",
+							  checkoids->data);
+		}
 
 		res = ExecuteSqlQuery(fout, q->data, PGRES_TUPLES_OK);
 
@@ -9225,6 +9260,7 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			Oid			conrelid = atooid(PQgetvalue(res, j, i_conrelid));
 			TableInfo  *tbinfo = NULL;
 			int			numcons;
+			int			ndumpablechecks;
 
 			/* Count rows for this table */
 			for (numcons = 1; numcons < numConstrs - j; numcons++)
@@ -9244,12 +9280,13 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 			if (curtblindx >= numTables)
 				pg_fatal("unrecognized table OID %u", conrelid);
 
-			if (numcons != tbinfo->ncheck)
+			ndumpablechecks = tbinfo->ncheck - tbinfo->nperiod;
+			if (numcons != ndumpablechecks)
 			{
 				pg_log_error(ngettext("expected %d check constraint on table \"%s\" but found %d",
 									  "expected %d check constraints on table \"%s\" but found %d",
-									  tbinfo->ncheck),
-							 tbinfo->ncheck, tbinfo->dobj.name, numcons);
+									  ndumpablechecks),
+							 ndumpablechecks, tbinfo->dobj.name, numcons);
 				pg_log_error_hint("The system catalogs might be corrupted.");
 				exit_nicely(1);
 			}
@@ -9308,6 +9345,80 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables)
 		PQclear(res);
 	}
 
+	for (int i = 0; i < numTables; i++)
+	{
+		TableInfo  *tbinfo = &tblinfo[i];
+
+		/*
+		 * Get info about PERIOD definitions
+		 */
+		if (tbinfo->nperiod > 0)
+		{
+			PeriodInfo *periods;
+			int			numPeriods;
+			int			j;
+
+			/* We shouldn't have any periods before v17 */
+			Assert(fout->remoteVersion >= 170000);
+
+			pg_log_info("finding periods for table \"%s.%s\"",
+						tbinfo->dobj.namespace->dobj.name,
+						tbinfo->dobj.name);
+
+			resetPQExpBuffer(q);
+			appendPQExpBuffer(q,
+				"SELECT p.tableoid, p.oid, p.pername, "
+				"       sa.attname AS perstart, ea.attname AS perend, "
+				"       r.typname AS rngtype, "
+				"       c.conname AS conname "
+				"FROM pg_catalog.pg_period AS p "
+				"JOIN pg_catalog.pg_attribute AS sa ON (sa.attrelid, sa.attnum) = (p.perrelid, p.perstart) "
+				"JOIN pg_catalog.pg_attribute AS ea ON (ea.attrelid, ea.attnum) = (p.perrelid, p.perend) "
+				"JOIN pg_catalog.pg_attribute AS ra ON (ra.attrelid, ra.attnum) = (p.perrelid, p.perrange) "
+				"JOIN pg_catalog.pg_type AS r ON r.oid = ra.atttypid "
+				"JOIN pg_catalog.pg_constraint AS c ON c.oid = p.perconstraint "
+				"WHERE p.perrelid = '%u'::pg_catalog.oid "
+				"ORDER BY p.pername",
+				tbinfo->dobj.catId.oid);
+
+			res = ExecuteSqlQuery(fout, q->data, PGRES_TUPLES_OK);
+
+			/*
+			 * If we didn't get the number of rows we thought we were going to,
+			 * then those JOINs didn't work.
+			 */
+			numPeriods = PQntuples(res);
+			if (numPeriods != tbinfo->nperiod)
+			{
+				pg_log_info(ngettext("expected %d period on table \"%s\" but found %d",
+									 "expected %d periods on table \"%s\" but found %d",
+									 tbinfo->nperiod),
+							tbinfo->nperiod, tbinfo->dobj.name, numPeriods);
+				pg_log_info("(The system catalogs might be corrupted.)");
+				exit_nicely(1);
+			}
+
+			periods = (PeriodInfo *) pg_malloc(numPeriods * sizeof(PeriodInfo));
+			tbinfo->periods = periods;
+
+			for (j = 0; j < numPeriods; j++)
+			{
+				periods[j].dobj.objType = DO_PERIOD;
+				periods[j].dobj.catId.tableoid = atooid(PQgetvalue(res, j, 0));
+				periods[j].dobj.catId.oid = atooid(PQgetvalue(res, j, 1));
+				AssignDumpId(&periods[j].dobj);
+				periods[j].dobj.name = pg_strdup(PQgetvalue(res, j, 2));
+				periods[j].dobj.namespace = tbinfo->dobj.namespace;
+				periods[j].pertable = tbinfo;
+				periods[j].perstart = pg_strdup(PQgetvalue(res, j, 3));
+				periods[j].perend = pg_strdup(PQgetvalue(res, j, 4));
+				periods[j].rngtype = pg_strdup(PQgetvalue(res, j, 5));
+				periods[j].conname = pg_strdup(PQgetvalue(res, j, 6));
+			}
+			PQclear(res);
+		}
+	}
+
 	destroyPQExpBuffer(q);
 	destroyPQExpBuffer(tbloids);
 	destroyPQExpBuffer(checkoids);
@@ -10578,6 +10689,8 @@ dumpDumpableObject(Archive *fout, DumpableObject *dobj)
 		case DO_FK_CONSTRAINT:
 			dumpConstraint(fout, (const ConstraintInfo *) dobj);
 			break;
+		case DO_PERIOD:
+			break;
 		case DO_PROCLANG:
 			dumpProcLang(fout, (const ProcLangInfo *) dobj);
 			break;
@@ -16130,6 +16243,33 @@ dumpTableSchema(Archive *fout, const TableInfo *tbinfo)
 				}
 			}
 
+			/*
+			 * Add non-inherited PERIOD definitions, if any.
+			 */
+			for (j = 0; j < tbinfo->nperiod; j++)
+			{
+				PeriodInfo *period = &(tbinfo->periods[j]);
+
+				char	   *name = pg_strdup(fmtId(period->dobj.name));
+				char	   *start = pg_strdup(fmtId(period->perstart));
+				char	   *end = pg_strdup(fmtId(period->perend));
+				char	   *rngtype = pg_strdup(fmtId(period->rngtype));
+				char	   *conname = pg_strdup(fmtId(period->conname));
+
+				if (actual_atts == 0)
+					appendPQExpBufferStr(q, " (\n    ");
+				else
+					appendPQExpBufferStr(q, ",\n    ");
+
+				/* Always say colexists so we can just print the GENERATED column */
+				appendPQExpBuffer(q, "PERIOD FOR %s (%s, %s) "
+						"WITH (rangetype = %s, check_constraint_name = %s, colexists = true)",
+								  name, start, end,
+								  rngtype, conname);
+
+				actual_atts++;
+			}
+
 			/*
 			 * Add non-inherited CHECK constraints, if any.
 			 *
@@ -16138,7 +16278,7 @@ dumpTableSchema(Archive *fout, const TableInfo *tbinfo)
 			 * PARTITION that we'll emit later expects the constraint to be
 			 * there.  (No need to fix conislocal: ATTACH PARTITION does that)
 			 */
-			for (j = 0; j < tbinfo->ncheck; j++)
+			for (j = 0; j < tbinfo->ncheck - tbinfo->nperiod; j++)
 			{
 				ConstraintInfo *constr = &(tbinfo->checkexprs[j]);
 
@@ -16356,7 +16496,7 @@ dumpTableSchema(Archive *fout, const TableInfo *tbinfo)
 			 * For partitions, they were already dumped, and conislocal
 			 * doesn't need fixing.
 			 */
-			for (k = 0; k < tbinfo->ncheck; k++)
+			for (k = 0; k < tbinfo->ncheck - tbinfo->nperiod; k++)
 			{
 				ConstraintInfo *constr = &(tbinfo->checkexprs[k]);
 
@@ -16658,7 +16798,7 @@ dumpTableSchema(Archive *fout, const TableInfo *tbinfo)
 		dumpTableSecLabel(fout, tbinfo, reltypename);
 
 	/* Dump comments on inlined table constraints */
-	for (j = 0; j < tbinfo->ncheck; j++)
+	for (j = 0; j < tbinfo->ncheck - tbinfo->nperiod; j++)
 	{
 		ConstraintInfo *constr = &(tbinfo->checkexprs[j]);
 
@@ -18627,6 +18767,7 @@ addBoundaryDependencies(DumpableObject **dobjs, int numObjs,
 			case DO_TRIGGER:
 			case DO_EVENT_TRIGGER:
 			case DO_DEFAULT_ACL:
+			case DO_PERIOD:
 			case DO_POLICY:
 			case DO_PUBLICATION:
 			case DO_PUBLICATION_REL:
diff --git a/src/bin/pg_dump/pg_dump.h b/src/bin/pg_dump/pg_dump.h
index 9bc93520b45..04c9f15f6eb 100644
--- a/src/bin/pg_dump/pg_dump.h
+++ b/src/bin/pg_dump/pg_dump.h
@@ -59,6 +59,7 @@ typedef enum
 	DO_TRIGGER,
 	DO_CONSTRAINT,
 	DO_FK_CONSTRAINT,			/* see note for ConstraintInfo */
+	DO_PERIOD,
 	DO_PROCLANG,
 	DO_CAST,
 	DO_TABLE_DATA,
@@ -300,12 +301,14 @@ typedef struct _tableInfo
 	bool		rowsec;			/* is row security enabled? */
 	bool		forcerowsec;	/* is row security forced? */
 	bool		hasoids;		/* does it have OIDs? */
+	bool		hasperiods;		/* does it have any periods? */
 	uint32		frozenxid;		/* table's relfrozenxid */
 	uint32		minmxid;		/* table's relminmxid */
 	Oid			toast_oid;		/* toast table's OID, or 0 if none */
 	uint32		toast_frozenxid;	/* toast table's relfrozenxid, if any */
 	uint32		toast_minmxid;	/* toast table's relminmxid */
 	int			ncheck;			/* # of CHECK expressions */
+	int			nperiod;		/* # of PERIOD definitions */
 	Oid			reltype;		/* OID of table's composite type, if any */
 	Oid			reloftype;		/* underlying type for typed table */
 	Oid			foreign_server; /* foreign server oid, if applicable */
@@ -336,6 +339,7 @@ typedef struct _tableInfo
 	char	   *attstorage;		/* attribute storage scheme */
 	char	   *typstorage;		/* type storage scheme */
 	bool	   *attisdropped;	/* true if attr is dropped; don't dump it */
+	bool	   *attisperiod;	/* true if attr is a PERIOD; don't dump it */
 	char	   *attidentity;
 	char	   *attgenerated;
 	int		   *attlen;			/* attribute length, used by binary_upgrade */
@@ -355,6 +359,7 @@ typedef struct _tableInfo
 	bool	   *notnull_inh;	/* true if NOT NULL has no local definition */
 	struct _attrDefInfo **attrdefs; /* DEFAULT expressions */
 	struct _constraintInfo *checkexprs; /* CHECK constraints */
+	struct _periodInfo *periods;	/* PERIOD definitions */
 	bool		needs_override; /* has GENERATED ALWAYS AS IDENTITY */
 	char	   *amname;			/* relation access method */
 
@@ -484,6 +489,16 @@ typedef struct _constraintInfo
 	bool		separate;		/* true if must dump as separate item */
 } ConstraintInfo;
 
+typedef struct _periodInfo
+{
+	DumpableObject dobj;
+	TableInfo  *pertable;
+	char	   *perstart;		/* the name of the start column */
+	char	   *perend;			/* the name of the end column */
+	char	   *rngtype;		/* the name of the range type */
+	char	   *conname;		/* the name of the CHECK constraint */
+} PeriodInfo;
+
 typedef struct _procLangInfo
 {
 	DumpableObject dobj;
diff --git a/src/bin/pg_dump/pg_dump_sort.c b/src/bin/pg_dump/pg_dump_sort.c
index 4cb754caa55..5602cda4d5c 100644
--- a/src/bin/pg_dump/pg_dump_sort.c
+++ b/src/bin/pg_dump/pg_dump_sort.c
@@ -86,6 +86,7 @@ enum dbObjectTypePriorities
 	PRIO_CONSTRAINT,
 	PRIO_INDEX,
 	PRIO_INDEX_ATTACH,
+	PRIO_PERIOD,
 	PRIO_STATSEXT,
 	PRIO_RULE,
 	PRIO_TRIGGER,
@@ -121,6 +122,7 @@ static const int dbObjectTypePriority[] =
 	[DO_ATTRDEF] = PRIO_ATTRDEF,
 	[DO_INDEX] = PRIO_INDEX,
 	[DO_INDEX_ATTACH] = PRIO_INDEX_ATTACH,
+	[DO_PERIOD] = PRIO_PERIOD,
 	[DO_STATSEXT] = PRIO_STATSEXT,
 	[DO_RULE] = PRIO_RULE,
 	[DO_TRIGGER] = PRIO_TRIGGER,
@@ -1371,6 +1373,11 @@ describeDumpableObject(DumpableObject *obj, char *buf, int bufsize)
 					 "FK CONSTRAINT %s  (ID %d OID %u)",
 					 obj->name, obj->dumpId, obj->catId.oid);
 			return;
+		case DO_PERIOD:
+			snprintf(buf, bufsize,
+					 "PERIOD %s  (ID %d OID %u)",
+					 obj->name, obj->dumpId, obj->catId.oid);
+			return;
 		case DO_PROCLANG:
 			snprintf(buf, bufsize,
 					 "PROCEDURAL LANGUAGE %s  (ID %d OID %u)",
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 1ab80eb7cac..6a312e99cfe 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -1947,6 +1947,8 @@ describeOneTableDetails(const char *schemaname,
 
 	appendPQExpBufferStr(&buf, "\nFROM pg_catalog.pg_attribute a");
 	appendPQExpBuffer(&buf, "\nWHERE a.attrelid = '%s' AND a.attnum > 0 AND NOT a.attisdropped", oid);
+	if (pset.sversion >= 170000)
+		appendPQExpBuffer(&buf, "\nAND NOT EXISTS (SELECT 1 FROM pg_catalog.pg_period p WHERE p.perrelid = a.attrelid AND p.perrange = a.attnum)");
 	appendPQExpBufferStr(&buf, "\nORDER BY a.attnum;");
 
 	res = PSQLexec(buf.data);
@@ -2369,6 +2371,40 @@ describeOneTableDetails(const char *schemaname,
 		PGresult   *result = NULL;
 		int			tuples = 0;
 
+		/* print periods */
+		if (pset.sversion >= 170000)
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT quote_ident(p.pername), quote_ident(s.attname) AS startatt, quote_ident(e.attname) AS endatt\n"
+							  "FROM pg_period AS p\n"
+							  "JOIN pg_attribute AS s ON (s.attrelid, s.attnum) = (p.perrelid, p.perstart)\n"
+							  "JOIN pg_attribute AS e ON (e.attrelid, e.attnum) = (p.perrelid, p.perend)\n"
+							  "WHERE p.perrelid = '%s'\n"
+							  "ORDER BY 1;",
+							  oid);
+			result = PSQLexec(buf.data);
+			if (!result)
+				goto error_return;
+			else
+				tuples = PQntuples(result);
+
+			if (tuples > 0)
+			{
+				printTableAddFooter(&cont, _("Periods:"));
+				for (i = 0; i < tuples; i++)
+				{
+					/* untranslated constraint name and def */
+					printfPQExpBuffer(&buf, "    %s (%s, %s)",
+									  PQgetvalue(result, i, 0),
+									  PQgetvalue(result, i, 1),
+									  PQgetvalue(result, i, 2));
+
+					printTableAddFooter(&cont, buf.data);
+				}
+			}
+			PQclear(result);
+		}
+
 		/* print indexes */
 		if (tableinfo.hasindex)
 		{
diff --git a/src/include/catalog/Makefile b/src/include/catalog/Makefile
index 167f91a6e3f..62bb4fc63fb 100644
--- a/src/include/catalog/Makefile
+++ b/src/include/catalog/Makefile
@@ -65,6 +65,7 @@ CATALOG_HEADERS := \
 	pg_foreign_server.h \
 	pg_user_mapping.h \
 	pg_foreign_table.h \
+	pg_period.h \
 	pg_policy.h \
 	pg_replication_origin.h \
 	pg_default_acl.h \
diff --git a/src/include/catalog/dependency.h b/src/include/catalog/dependency.h
index 436b081738b..45623e86a45 100644
--- a/src/include/catalog/dependency.h
+++ b/src/include/catalog/dependency.h
@@ -93,6 +93,7 @@ typedef enum ObjectClass
 	OCLASS_CAST,				/* pg_cast */
 	OCLASS_COLLATION,			/* pg_collation */
 	OCLASS_CONSTRAINT,			/* pg_constraint */
+	OCLASS_PERIOD,				/* pg_period */
 	OCLASS_CONVERSION,			/* pg_conversion */
 	OCLASS_DEFAULT,				/* pg_attrdef */
 	OCLASS_LANGUAGE,			/* pg_language */
diff --git a/src/include/catalog/heap.h b/src/include/catalog/heap.h
index 1d7f8380d90..3592a444bd1 100644
--- a/src/include/catalog/heap.h
+++ b/src/include/catalog/heap.h
@@ -121,6 +121,10 @@ extern List *AddRelationNotNullConstraints(Relation rel,
 extern void RelationClearMissing(Relation rel);
 extern void SetAttrMissing(Oid relid, char *attname, char *value);
 
+extern Oid StorePeriod(Relation rel, const char *period,
+					   AttrNumber startnum, AttrNumber endnum,
+					   AttrNumber rangenum, Oid conoid);
+
 extern Node *cookDefault(ParseState *pstate,
 						 Node *raw_default,
 						 Oid atttypid,
diff --git a/src/include/catalog/meson.build b/src/include/catalog/meson.build
index f70d1daba52..d45aa5fa863 100644
--- a/src/include/catalog/meson.build
+++ b/src/include/catalog/meson.build
@@ -61,6 +61,7 @@ catalog_headers = [
   'pg_collation.h',
   'pg_parameter_acl.h',
   'pg_partitioned_table.h',
+  'pg_period.h',
   'pg_range.h',
   'pg_transform.h',
   'pg_sequence.h',
diff --git a/src/include/catalog/pg_index.h b/src/include/catalog/pg_index.h
index 3462572eb55..0a3c8111b67 100644
--- a/src/include/catalog/pg_index.h
+++ b/src/include/catalog/pg_index.h
@@ -48,7 +48,6 @@ CATALOG(pg_index,2610,IndexRelationId) BKI_SCHEMA_MACRO
 	/* variable-length fields start here, but we allow direct access to indkey */
 	int2vector	indkey BKI_FORCE_NOT_NULL;	/* column numbers of indexed cols,
 											 * or 0 */
-
 #ifdef CATALOG_VARLEN
 	oidvector	indcollation BKI_LOOKUP_OPT(pg_collation) BKI_FORCE_NOT_NULL;	/* collation identifiers */
 	oidvector	indclass BKI_LOOKUP(pg_opclass) BKI_FORCE_NOT_NULL; /* opclass identifiers */
diff --git a/src/include/catalog/pg_period.h b/src/include/catalog/pg_period.h
new file mode 100644
index 00000000000..2508cd45a09
--- /dev/null
+++ b/src/include/catalog/pg_period.h
@@ -0,0 +1,58 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_period.h
+ *	  definition of the "period" system catalog (pg_period)
+ *
+ *
+ * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
+ *
+ * src/include/catalog/pg_period.h
+ *
+ * NOTES
+ *	  The Catalog.pm module reads this file and derives schema
+ *	  information.
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_PERIOD_H
+#define PG_PERIOD_H
+
+#include "catalog/genbki.h"
+#include "catalog/pg_period_d.h"
+#include "nodes/bitmapset.h"
+
+/* ----------------
+ *		pg_period definition.  cpp turns this into
+ *		typedef struct FormData_pg_period
+ * ----------------
+ */
+CATALOG(pg_period,8000,PeriodRelationId)
+{
+	Oid			oid;			/* OID of the period */
+	NameData	pername;		/* name of period */
+	Oid			perrelid;		/* OID of relation containing this period */
+	int16		perstart;		/* column for start value */
+	int16		perend;			/* column for end value */
+	int16		perrange;		/* column for range value */
+	Oid			perconstraint;	/* OID of (start < end) constraint */
+} FormData_pg_period;
+
+/* ----------------
+ *		Form_pg_period corresponds to a pointer to a tuple with
+ *		the format of pg_period relation.
+ * ----------------
+ */
+typedef FormData_pg_period *Form_pg_period;
+
+DECLARE_UNIQUE_INDEX_PKEY(pg_period_oid_index, 8001, PeriodObjectIndexId, pg_period, btree(oid oid_ops));
+DECLARE_UNIQUE_INDEX(pg_period_perrelid_pername_index, 8002, PeriodRelidNameIndexId, pg_period, btree(perrelid oid_ops, pername name_ops));
+
+MAKE_SYSCACHE(PERIODOID, pg_period_oid_index, 32);
+MAKE_SYSCACHE(PERIODNAME, pg_period_perrelid_pername_index, 32);
+
+extern void RemovePeriodById(Oid periodId);
+
+extern Oid get_relation_period_oid(Oid relid, const char *pername, bool missing_ok);
+extern Bitmapset *get_period_attnos(Oid relid);
+
+#endif							/* PG_PERIOD_H */
diff --git a/src/include/catalog/pg_range.h b/src/include/catalog/pg_range.h
index 0bd3ab688bd..10a94dd11f1 100644
--- a/src/include/catalog/pg_range.h
+++ b/src/include/catalog/pg_range.h
@@ -59,8 +59,10 @@ typedef FormData_pg_range *Form_pg_range;
 
 DECLARE_UNIQUE_INDEX_PKEY(pg_range_rngtypid_index, 3542, RangeTypidIndexId, pg_range, btree(rngtypid oid_ops));
 DECLARE_UNIQUE_INDEX(pg_range_rngmultitypid_index, 2228, RangeMultirangeTypidIndexId, pg_range, btree(rngmultitypid oid_ops));
+DECLARE_UNIQUE_INDEX(pg_range_rngsubtype_rngtypid_index, 8003, RangeSubTypidTypidIndexId, pg_range, btree(rngsubtype oid_ops, rngtypid oid_ops));
 
 MAKE_SYSCACHE(RANGETYPE, pg_range_rngtypid_index, 4);
+MAKE_SYSCACHE(RANGESUBTYPE, pg_range_rngsubtype_rngtypid_index, 4);
 MAKE_SYSCACHE(RANGEMULTIRANGE, pg_range_rngmultitypid_index, 4);
 
 /*
diff --git a/src/include/commands/tablecmds.h b/src/include/commands/tablecmds.h
index 85cbad3d0c2..628fa53796c 100644
--- a/src/include/commands/tablecmds.h
+++ b/src/include/commands/tablecmds.h
@@ -40,7 +40,8 @@ extern LOCKMODE AlterTableGetLockLevel(List *cmds);
 
 extern void ATExecChangeOwner(Oid relationOid, Oid newOwnerId, bool recursing, LOCKMODE lockmode);
 
-extern void AlterTableInternal(Oid relid, List *cmds, bool recurse);
+extern void AlterTableInternal(Oid relid, List *cmds, bool recurse,
+							   struct AlterTableUtilityContext *context);
 
 extern Oid	AlterTableMoveAll(AlterTableMoveAllStmt *stmt);
 
@@ -106,5 +107,6 @@ extern void RangeVarCallbackOwnsRelation(const RangeVar *relation,
 										 Oid relId, Oid oldRelId, void *arg);
 extern bool PartConstraintImpliedByRelConstraint(Relation scanrel,
 												 List *partConstraint);
+extern Oid choose_rangetype_for_period(PeriodDef *period);
 
 #endif							/* TABLECMDS_H */
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index c839c8fb2a7..9a40251f260 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2153,6 +2153,7 @@ typedef enum ObjectType
 	OBJECT_OPERATOR,
 	OBJECT_OPFAMILY,
 	OBJECT_PARAMETER_ACL,
+	OBJECT_PERIOD,
 	OBJECT_POLICY,
 	OBJECT_PROCEDURE,
 	OBJECT_PUBLICATION,
@@ -2241,6 +2242,8 @@ typedef enum AlterTableType
 	AT_ValidateConstraint,		/* validate constraint */
 	AT_AddIndexConstraint,		/* add constraint using existing index */
 	AT_DropConstraint,			/* drop constraint */
+	AT_AddPeriod,				/* ADD PERIOD */
+	AT_DropPeriod,				/* DROP PERIOD */
 	AT_ReAddComment,			/* internal to commands/tablecmds.c */
 	AT_AlterColumnType,			/* alter column type */
 	AT_AlterColumnGenericOptions,	/* alter column OPTIONS (...) */
@@ -2507,11 +2510,11 @@ typedef struct VariableShowStmt
 /* ----------------------
  *		Create Table Statement
  *
- * NOTE: in the raw gram.y output, ColumnDef and Constraint nodes are
- * intermixed in tableElts, and constraints and nnconstraints are NIL.  After
- * parse analysis, tableElts contains just ColumnDefs, nnconstraints contains
- * Constraint nodes of CONSTR_NOTNULL type from various sources, and
- * constraints contains just CONSTR_CHECK Constraint nodes.
+ * NOTE: in the raw gram.y output, ColumnDef, PeriodDef, and Constraint nodes are
+ * intermixed in tableElts; periods, constraints, and nnconstraints are NIL.  After
+ * parse analysis, tableElts contains just ColumnDefs, periods contains just PeriodDefs,
+ * nnconstraints contains Constraint nodes of CONSTR_NOTNULL type from various sources,
+ * and constraints contains just CONSTR_CHECK Constraint nodes.
  * ----------------------
  */
 
@@ -2520,6 +2523,7 @@ typedef struct CreateStmt
 	NodeTag		type;
 	RangeVar   *relation;		/* relation to create */
 	List	   *tableElts;		/* column definitions (list of ColumnDef) */
+	List	   *periods;		/* periods (list of PeriodDef nodes) */
 	List	   *inhRelations;	/* relations to inherit from (list of
 								 * RangeVar) */
 	PartitionBoundSpec *partbound;	/* FOR VALUES clause */
@@ -2534,6 +2538,31 @@ typedef struct CreateStmt
 	bool		if_not_exists;	/* just do nothing if it already exists? */
 } CreateStmt;
 
+
+/* ----------
+ * Definitions for periods in CreateStmt
+ * ----------
+ */
+
+typedef struct PeriodDef
+{
+	NodeTag		type;
+	Oid			oid;			/* period oid, once it's transformed */
+	char	   *periodname;		/* period name */
+	char	   *startcolname;	/* name of start column */
+	char	   *endcolname;		/* name of end column */
+	AttrNumber	startattnum;	/* attnum of the start column */
+	AttrNumber	endattnum;		/* attnum of the end column */
+	AttrNumber	rngattnum;		/* attnum of the GENERATED range column */
+	List	   *options;		/* options from WITH clause */
+	char	   *constraintname;	/* name of the CHECK constraint */
+	char	   *rangetypename;	/* name of the range type */
+	Oid			coltypid;		/* the start/end col type */
+	Oid			rngtypid;		/* the range type to use */
+	bool		colexists;		/* use an existing GENERATED column */
+	int			location;		/* token location, or -1 if unknown */
+} PeriodDef;
+
 /* ----------
  * Definitions for constraints in CreateStmt
  *
@@ -3229,6 +3258,7 @@ typedef struct IndexStmt
 	List	   *indexParams;	/* columns to index: a list of IndexElem */
 	List	   *indexIncludingParams;	/* additional columns to index: a list
 										 * of IndexElem */
+	PeriodDef  *period;			/* The period included in the index */
 	List	   *options;		/* WITH clause options: a list of DefElem */
 	Node	   *whereClause;	/* qualification (partial-index predicate) */
 	List	   *excludeOpNames; /* exclusion operator names, or NIL if none */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index ea6701d83ca..e7294e03027 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -2086,6 +2086,8 @@ typedef struct ForPortionOfExpr
 {
 	NodeTag		type;
 	Var		   *rangeVar;			/* Range column */
+	Var		   *startVar;			/* Start column if PERIOD */
+	Var		   *endVar;				/* End column if PERIOD */
 	char	   *range_name;			/* Range name */
 	Node	   *targetRange;		/* FOR PORTION OF bounds as a range */
 	Oid			rangeType;			/* type of targetRange */
diff --git a/src/include/parser/kwlist.h b/src/include/parser/kwlist.h
index 4e9b48fff66..707a517339a 100644
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@@ -326,7 +326,7 @@ PG_KEYWORD("partial", PARTIAL, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("partition", PARTITION, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("passing", PASSING, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("password", PASSWORD, UNRESERVED_KEYWORD, BARE_LABEL)
-PG_KEYWORD("period", PERIOD, UNRESERVED_KEYWORD, BARE_LABEL)
+PG_KEYWORD("period", PERIOD, RESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("placing", PLACING, RESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("plans", PLANS, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("policy", POLICY, UNRESERVED_KEYWORD, BARE_LABEL)
diff --git a/src/include/parser/parse_utilcmd.h b/src/include/parser/parse_utilcmd.h
index 14065894779..d84d02b0280 100644
--- a/src/include/parser/parse_utilcmd.h
+++ b/src/include/parser/parse_utilcmd.h
@@ -40,5 +40,6 @@ extern IndexStmt *generateClonedIndexStmt(RangeVar *heapRel,
 										  Relation source_idx,
 										  const struct AttrMap *attmap,
 										  Oid *constraintOid);
+extern void transformPeriodOptions(PeriodDef *period);
 
 #endif							/* PARSE_UTILCMD_H */
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 48df107c1ce..cd9fe5c988d 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -95,6 +95,8 @@ extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 								  Oid *typid, int32 *typmod, Oid *collid);
 extern Datum get_attoptions(Oid relid, int16 attnum);
+extern char *get_periodname(Oid periodid, bool missing_ok);
+extern Oid	get_period_oid(Oid relid, const char *periodname, bool missing_ok);
 extern Oid	get_cast_oid(Oid sourcetypeid, Oid targettypeid, bool missing_ok);
 extern char *get_collation_name(Oid colloid);
 extern bool get_collation_isdeterministic(Oid colloid);
@@ -196,6 +198,7 @@ extern Oid	get_range_subtype(Oid rangeOid);
 extern Oid	get_range_collation(Oid rangeOid);
 extern Oid	get_range_multirange(Oid rangeOid);
 extern Oid	get_multirange_range(Oid multirangeOid);
+extern Oid	get_subtype_range(Oid subtypeOid);
 extern Oid	get_index_column_opclass(Oid index_oid, int attno);
 extern bool get_index_isreplident(Oid index_oid);
 extern bool get_index_isvalid(Oid index_oid);
diff --git a/src/include/utils/period.h b/src/include/utils/period.h
new file mode 100644
index 00000000000..d02c17036fd
--- /dev/null
+++ b/src/include/utils/period.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * period.h
+ *	  support for Postgres periods.
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/utils/period.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PERIOD_H
+#define PERIOD_H
+
+#include "executor/tuptable.h"
+
+extern Datum period_to_range(TupleTableSlot *slot, int startattno, int endattno, Oid rangetype);
+
+#endif							/* PERIOD_H */
diff --git a/src/test/modules/test_ddl_deparse/test_ddl_deparse.c b/src/test/modules/test_ddl_deparse/test_ddl_deparse.c
index 48563b2cf01..a954e703384 100644
--- a/src/test/modules/test_ddl_deparse/test_ddl_deparse.c
+++ b/src/test/modules/test_ddl_deparse/test_ddl_deparse.c
@@ -183,6 +183,12 @@ get_altertable_subcmdinfo(PG_FUNCTION_ARGS)
 			case AT_DropConstraint:
 				strtype = "DROP CONSTRAINT";
 				break;
+			case AT_AddPeriod:
+				strtype = "ADD PERIOD";
+				break;
+			case AT_DropPeriod:
+				strtype = "DROP PERIOD";
+				break;
 			case AT_ReAddComment:
 				strtype = "(re) ADD COMMENT";
 				break;
diff --git a/src/test/regress/expected/for_portion_of.out b/src/test/regress/expected/for_portion_of.out
index 5c0a5cf4b1b..ebc43f55f32 100644
--- a/src/test/regress/expected/for_portion_of.out
+++ b/src/test/regress/expected/for_portion_of.out
@@ -532,6 +532,44 @@ SELECT * FROM for_portion_of_test2 ORDER BY id, valid_at;
  [3,4) | {[01-01-2018,)}                                                           | three
 (6 rows)
 
+DROP TABLE for_portion_of_test2;
+-- Test with PERIODs
+CREATE TABLE for_portion_of_test2 (
+  id int4range NOT NULL,
+  valid_from date,
+  valid_til date,
+  name text NOT NULL,
+  PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT for_portion_of_test2_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+INSERT INTO for_portion_of_test2
+VALUES
+('[1,2)', '2018-01-02', '2018-02-03', 'one'),
+('[1,2)', '2018-02-04', '2018-03-03', 'one'),
+('[1,2)', '2018-03-03', '2018-04-04', 'one'),
+('[2,3)', '2018-01-01', '2018-05-01', 'two'),
+('[3,4)', '2018-01-01', null, 'three');
+;
+UPDATE for_portion_of_test2
+FOR PORTION OF valid_at FROM '2018-01-10' TO '2018-02-10'
+SET name = 'one^1'
+WHERE id = '[1,2)';
+DELETE FROM for_portion_of_test2
+FOR PORTION OF valid_at FROM '2018-01-15' TO '2018-02-15'
+WHERE id = '[2,3)';
+SELECT * FROM for_portion_of_test2 ORDER BY id, valid_at;
+  id   | valid_from | valid_til  | name  
+-------+------------+------------+-------
+ [1,2) | 01-02-2018 | 01-10-2018 | one
+ [1,2) | 01-10-2018 | 02-03-2018 | one^1
+ [1,2) | 02-04-2018 | 02-10-2018 | one^1
+ [1,2) | 02-10-2018 | 03-03-2018 | one
+ [1,2) | 03-03-2018 | 04-04-2018 | one
+ [2,3) | 01-01-2018 | 01-15-2018 | two
+ [2,3) | 02-15-2018 | 05-01-2018 | two
+ [3,4) | 01-01-2018 |            | three
+(8 rows)
+
 DROP TABLE for_portion_of_test2;
 -- Test with a custom range type
 CREATE TYPE mydaterange AS range(subtype=date);
diff --git a/src/test/regress/expected/generated.out b/src/test/regress/expected/generated.out
index a4f37736623..d9c1f78ed8b 100644
--- a/src/test/regress/expected/generated.out
+++ b/src/test/regress/expected/generated.out
@@ -19,7 +19,9 @@ SELECT table_name, column_name, dependent_column FROM information_schema.column_
  table_name | column_name | dependent_column 
 ------------+-------------+------------------
  gtest1     | a           | b
-(1 row)
+ pt         | de          | p
+ pt         | ds          | p
+(3 rows)
 
 \d gtest1
                             Table "public.gtest1"
diff --git a/src/test/regress/expected/periods.out b/src/test/regress/expected/periods.out
new file mode 100644
index 00000000000..efd3a846ab9
--- /dev/null
+++ b/src/test/regress/expected/periods.out
@@ -0,0 +1,267 @@
+/* System periods are not implemented */
+create table pt (id integer, ds date, de date, period for system_time (ds, de));
+ERROR:  PERIOD FOR SYSTEM_TIME is not supported
+LINE 2: create table pt (id integer, ds date, de date, period for sy...
+                                                       ^
+/* Periods must specify actual columns */
+create table pt (id integer, ds date, de date, period for p (bogus, de));
+ERROR:  column "bogus" of relation "pt" does not exist
+create table pt (id integer, ds date, de date, period for p (ds, bogus));
+ERROR:  column "bogus" of relation "pt" does not exist
+/* Data types must match exactly */
+create table pt (id integer, ds date, de timestamp, period for p (ds, de));
+ERROR:  start and end columns of period must be of same type
+create table pt (id integer, ds text collate "C", de text collate "POSIX", period for p (ds, de));
+ERROR:  start and end columns of period must have same collation
+/* Periods must have a default BTree operator class */
+create table pt (id integer, ds xml, de xml, period for p (ds, de));
+ERROR:  no range type for xml found for period p
+HINT:  You can define a custom range type with CREATE TYPE
+/* Period and column names are in the same namespace */
+create table pt (id integer, ds date, de date, period for ctid (ds, de));
+ERROR:  period name "ctid" conflicts with a system column name
+create table pt (id integer, ds date, de date, period for id (ds, de));
+ERROR:  period name "id" conflicts with a column name
+/* Period name can't be given more than once */
+create table pt (id integer, ds date, de date, period for p (ds, de), period for p (ds, de));
+ERROR:  period name "p" specified more than once
+/* Now make one that works */
+create table pt (id integer, ds date, de date, period for p (ds, de));
+/* SELECT * excludes the PERIOD */
+insert into pt values (1, '2000-01-01', '2001-01-01');
+select * from pt;
+ id |     ds     |     de     
+----+------------+------------
+  1 | 01-01-2000 | 01-01-2001
+(1 row)
+
+/* You can get it if you want */
+select *, p from pt;
+ id |     ds     |     de     |            p            
+----+------------+------------+-------------------------
+  1 | 01-01-2000 | 01-01-2001 | [01-01-2000,01-01-2001)
+(1 row)
+
+/* Two are okay */
+create table pt2 (id integer, ds date, de date, period for p1 (ds, de), period for p2 (ds, de));
+drop table pt2;
+/* Skip creating GENERATED column: works */
+create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored, period for p (ds, de) with (colexists = true));
+\d pt2
+                Table "public.pt2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ id     | integer |           |          | 
+ ds     | date    |           |          | 
+ de     | date    |           |          | 
+Periods:
+    p (ds, de)
+Check constraints:
+    "pt2_p_check" CHECK (ds < de)
+
+drop table pt2;
+/* Skip creating GENERATED column: fails because the col isn't there */
+create table pt2 (id integer, ds date, de date, period for p (ds, de) with (colexists = true));
+ERROR:  No column found with name p
+/* Skip creating GENERATED column: fails because the option has an invalid value */
+create table pt2 (id integer, ds date, de date, period for p (ds, de) with (colexists = 'whatever'));
+ERROR:  colexists requires a Boolean value
+/* Skip creating GENERATED column: fails because the column is not NOT NULL */
+create table pt2 (id integer, ds date, de date, p daterange generated always as (daterange(ds, de)) stored, period for p (ds, de) with (colexists = true));
+ERROR:  Period p uses a generated column that allows nulls
+/* Skip creating GENERATED column: fails because the column is not GENERATED */
+create table pt2 (id integer, ds date, de date, p daterange not null, period for p (ds, de) with (colexists = true));
+ERROR:  Period p uses a non-generated column
+/* Skip creating GENERATED column: fails because the column is GENERATED but with the wrong expression */
+-- TODO:
+-- create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(de, ds)) stored, period for p (ds, de) with (colexists = true));
+/* Skip creating GENERATED column: fails because the column is the wrong type */
+create table pt2 (id integer, ds date, de date, p tsrange not null generated always as (tsrange(ds, de)) stored, period for p (ds, de) with (colexists = true));
+ERROR:  Period p uses a generated column with the wrong type
+/* Skip creating GENERATED column: fails because the column is inherited */
+create table pt2parent (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+create table pt2 (period for p (ds, de) with (colexists = true)) inherits (pt2parent);
+ERROR:  Inheriting is not supported when a table has a PERIOD
+drop table pt2parent;
+/*
+ * ALTER TABLE tests
+ */
+alter table pt drop period for p;
+alter table pt add period for system_time (ds, de);
+ERROR:  PERIOD FOR SYSTEM_TIME is not supported
+alter table pt add period for p (ds, de);
+/* Adding a second one */
+create table pt2 (id integer, ds date, de date, period for p1 (ds, de));
+alter table pt2 add period for p2 (ds, de);
+drop table pt2;
+/* Can't drop its columns */
+alter table pt drop column ds;
+ERROR:  cannot drop column ds of table pt because other objects depend on it
+DETAIL:  period p on table pt depends on column ds of table pt
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
+alter table pt drop column de;
+ERROR:  cannot drop column de of table pt because other objects depend on it
+DETAIL:  period p on table pt depends on column de of table pt
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
+/* Can't change the data types */
+alter table pt alter column ds type timestamp;
+ERROR:  cannot alter type of a column used by a period
+DETAIL:  period p on table pt depends on column "ds"
+alter table pt alter column ds type timestamp;
+ERROR:  cannot alter type of a column used by a period
+DETAIL:  period p on table pt depends on column "ds"
+/* column/period namespace conflicts */
+alter table pt add column p integer;
+ERROR:  column name "p" conflicts with a period name
+alter table pt rename column id to p;
+ERROR:  column name "p" conflicts with a period name
+alter table pt add period for tableoid (ds, de);
+ERROR:  period name "tableoid" conflicts with a system column name
+alter table pt add period for "........pg.dropped.4........" (ds, de);
+ERROR:  period name "........pg.dropped.4........" conflicts with a column name
+/* adding columns and the period at the same time */
+create table pt2 (id integer);
+alter table pt2 add column ds date, add column de date, add period for p (ds, de);
+drop table pt2;
+/* Ambiguous range types raise an error */
+create type mydaterange as range(subtype=date);
+create table pt2 (id int, ds date, de date, period for p (ds, de));
+ERROR:  ambiguous range for type date
+/* You can give an explicit range type */
+create table pt2 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'mydaterange'));
+drop type mydaterange;
+ERROR:  cannot drop type mydaterange because other objects depend on it
+DETAIL:  period p on table pt2 depends on type mydaterange
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
+drop type mydaterange cascade;
+NOTICE:  drop cascades to period p on table pt2
+drop table pt2;
+create table pt2 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'daterange'));
+/* Range type is not found */
+create table pt3 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'notarange'));
+ERROR:  Range type notarange not found
+/* Range type is the wrong type */
+create table pt3 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'tstzrange'));
+ERROR:  Range type tstzrange does not match column type date
+drop table pt2;
+/* Skip creating GENERATED column: works */
+create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+\d pt2
+                Table "public.pt2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ id     | integer |           |          | 
+ ds     | date    |           |          | 
+ de     | date    |           |          | 
+Periods:
+    p (ds, de)
+Check constraints:
+    "pt2_p_check" CHECK (ds < de)
+
+drop table pt2;
+/* Skip creating GENERATED column: fails because the col isn't there */
+create table pt2 (id integer, ds date, de date);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+ERROR:  column "p" of relation "pt2" does not exist
+drop table pt2;
+/* Skip creating GENERATED column: fails because the option has an invalid value */
+create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = 'whatever');
+ERROR:  colexists requires a Boolean value
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is not NOT NULL */
+create table pt2 (id integer, ds date, de date, p daterange generated always as (daterange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+ERROR:  Period p uses a generated column that allows nulls
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is not GENERATED */
+create table pt2 (id integer, ds date, de date, p daterange not null);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+ERROR:  Period p uses a non-generated column
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is GENERATED but with the wrong expression */
+-- TODO:
+-- create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(de, ds)) stored);
+-- alter table pt2 add period for p (ds, de) with (colexists = true);
+/* Skip creating GENERATED column: fails because the column is the wrong type */
+create table pt2 (id integer, ds date, de date, p tsrange not null generated always as (tsrange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+ERROR:  Period p uses a generated column with the wrong type
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is inherited */
+create table pt2parent (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+create table pt2 () inherits (pt2parent);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+ERROR:  Period p uses a generated column that is inherited
+drop table pt2;
+drop table pt2parent;
+/* CREATE TABLE (LIKE ...) */
+/* Periods are not copied by LIKE, so their columns aren't either */
+create table pt2 (like pt);
+\d pt2
+                Table "public.pt2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ id     | integer |           |          | 
+ ds     | date    |           |          | 
+ de     | date    |           |          | 
+
+drop table pt2;
+/* Can add a period referring to LIKE'd columns */
+create table not_p (id integer, ds date, de date);
+create table pt2 (like not_p, period for p (ds, de));
+\d pt2
+                Table "public.pt2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ id     | integer |           |          | 
+ ds     | date    |           |          | 
+ de     | date    |           |          | 
+Periods:
+    p (ds, de)
+Check constraints:
+    "pt2_p_check" CHECK (ds < de)
+
+drop table pt2;
+/* Can add a period with the same name */
+create table pt2 (like pt, period for p (ds, de));
+\d pt2
+                Table "public.pt2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ id     | integer |           |          | 
+ ds     | date    |           |          | 
+ de     | date    |           |          | 
+Periods:
+    p (ds, de)
+Check constraints:
+    "pt2_p_check" CHECK (ds < de)
+
+drop table pt2;
+/* Can add a period with a different name */
+create table pt2 (like pt, period for p2 (ds, de));
+\d pt2
+                Table "public.pt2"
+ Column |  Type   | Collation | Nullable | Default 
+--------+---------+-----------+----------+---------
+ id     | integer |           |          | 
+ ds     | date    |           |          | 
+ de     | date    |           |          | 
+Periods:
+    p2 (ds, de)
+Check constraints:
+    "pt2_p2_check" CHECK (ds < de)
+
+drop table pt2;
+/* Can't add a period whose name conflicts with a LIKE'd column */
+create table pt2 (like pt, period for id (ds, de));
+ERROR:  period name "id" conflicts with a column name
+/* CREATE TALBE INHERITS */
+/* Can't inherit from a table with a period */
+create table pt2 (name text) inherits (pt);
+ERROR:  Inheriting from a table with a PERIOD is not supported
+/* Can't inherit with a period */
+create table pt2 (d2s date, d2e date, period for p (d2s, d2e)) inherits (not_p);
+ERROR:  Inheriting is not supported when a table has a PERIOD
+drop table not_p;
diff --git a/src/test/regress/expected/without_overlaps.out b/src/test/regress/expected/without_overlaps.out
index a9712725809..18edbd71771 100644
--- a/src/test/regress/expected/without_overlaps.out
+++ b/src/test/regress/expected/without_overlaps.out
@@ -89,6 +89,76 @@ SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'te
  CREATE UNIQUE INDEX temporal_rng2_pk ON temporal_rng2 USING gist (id1, id2, valid_at)
 (1 row)
 
+-- PK with one column plus a PERIOD:
+CREATE TABLE temporal_per (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per
+               Table "public.temporal_per"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           | not null | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal_per_pk" PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal_per_valid_at_check" CHECK (valid_from < valid_til)
+
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per_pk';
+            pg_get_constraintdef             
+---------------------------------------------
+ PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+(1 row)
+
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per_pk';
+                                pg_get_indexdef                                
+-------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX temporal_per_pk ON temporal_per USING gist (id, valid_at)
+(1 row)
+
+-- PK with two columns plus a PERIOD:
+CREATE TABLE temporal_per2 (
+  id1 int4range,
+  id2 int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per2_pk PRIMARY KEY (id1, id2, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per2
+              Table "public.temporal_per2"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id1        | int4range |           | not null | 
+ id2        | int4range |           | not null | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal_per2_pk" PRIMARY KEY (id1, id2, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal_per2_valid_at_check" CHECK (valid_from < valid_til)
+
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per2_pk';
+               pg_get_constraintdef                
+---------------------------------------------------
+ PRIMARY KEY (id1, id2, valid_at WITHOUT OVERLAPS)
+(1 row)
+
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per2_pk';
+                                    pg_get_indexdef                                    
+---------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX temporal_per2_pk ON temporal_per2 USING gist (id1, id2, valid_at)
+(1 row)
+
 -- PK with a custom range type:
 CREATE TYPE textrange2 AS range (subtype=text, collation="C");
 CREATE TABLE temporal_rng3 (
@@ -224,6 +294,78 @@ SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'te
 (1 row)
 
 DROP TABLE temporal_rng3;
+-- UNIQUE with one column plus a PERIOD:
+CREATE TABLE temporal_per3 (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per3_uq UNIQUE (id, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per3
+              Table "public.temporal_per3"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           |          | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal_per3_uq" UNIQUE (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal_per3_valid_at_check" CHECK (valid_from < valid_til)
+
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+          pg_get_constraintdef          
+----------------------------------------
+ UNIQUE (id, valid_at WITHOUT OVERLAPS)
+(1 row)
+
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+                                 pg_get_indexdef                                 
+---------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX temporal_per3_uq ON temporal_per3 USING gist (id, valid_at)
+(1 row)
+
+DROP TABLE temporal_per3;
+-- UNIQUE with two columns plus a PERIOD:
+CREATE TABLE temporal_per3 (
+  id1 int4range,
+  id2 int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per3_uq UNIQUE (id1, id2, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per3
+              Table "public.temporal_per3"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id1        | int4range |           |          | 
+ id2        | int4range |           |          | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal_per3_uq" UNIQUE (id1, id2, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal_per3_valid_at_check" CHECK (valid_from < valid_til)
+
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+             pg_get_constraintdef             
+----------------------------------------------
+ UNIQUE (id1, id2, valid_at WITHOUT OVERLAPS)
+(1 row)
+
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+                                    pg_get_indexdef                                    
+---------------------------------------------------------------------------------------
+ CREATE UNIQUE INDEX temporal_per3_uq ON temporal_per3 USING gist (id1, id2, valid_at)
+(1 row)
+
+DROP TABLE temporal_per3;
 -- UNIQUE with a custom range type:
 CREATE TYPE textrange2 AS range (subtype=text, collation="C");
 CREATE TABLE temporal_rng3 (
@@ -302,6 +444,106 @@ ALTER TABLE temporal3
 	ADD CONSTRAINT temporal3_uq
 	UNIQUE (id, valid_at WITHOUT OVERLAPS);
 DROP TABLE temporal3;
+-- PRIMARY KEY with PERIOD already there
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til)
+);
+ALTER TABLE temporal3
+  ADD CONSTRAINT temporal3_pk
+  PRIMARY KEY (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+                Table "public.temporal3"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           | not null | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal3_pk" PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal3_valid_at_check" CHECK (valid_from < valid_til)
+
+DROP TABLE temporal3;
+-- PRIMARY KEY with PERIOD too
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date
+);
+ALTER TABLE temporal3
+  ADD PERIOD FOR valid_at (valid_from, valid_til),
+  ADD CONSTRAINT temporal3_pk
+  PRIMARY KEY (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+                Table "public.temporal3"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           | not null | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal3_pk" PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal3_valid_at_check" CHECK (valid_from < valid_til)
+
+DROP TABLE temporal3;
+-- UNIQUE with PERIOD already there
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til)
+);
+ALTER TABLE temporal3
+  ADD CONSTRAINT temporal3_uq
+  UNIQUE (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+                Table "public.temporal3"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           |          | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal3_uq" UNIQUE (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal3_valid_at_check" CHECK (valid_from < valid_til)
+
+DROP TABLE temporal3;
+-- UNIQUE with PERIOD too
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date
+);
+ALTER TABLE temporal3
+  ADD PERIOD FOR valid_at (valid_from, valid_til),
+  ADD CONSTRAINT temporal3_uq
+  UNIQUE (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+                Table "public.temporal3"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           |          | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal3_uq" UNIQUE (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal3_valid_at_check" CHECK (valid_from < valid_til)
+
+DROP TABLE temporal3;
 --
 -- test PK inserts
 --
@@ -592,6 +834,18 @@ CREATE TABLE temporal_fk_rng2rng (
 	CONSTRAINT temporal_fk_rng2rng_fk FOREIGN KEY (parent_id, PERIOD valid_at)
 		REFERENCES temporal_rng (id, PERIOD valid_at)
 );
+\d temporal_fk_rng2rng
+           Table "public.temporal_fk_rng2rng"
+  Column   |   Type    | Collation | Nullable | Default 
+-----------+-----------+-----------+----------+---------
+ id        | int4range |           | not null | 
+ valid_at  | daterange |           | not null | 
+ parent_id | int4range |           |          | 
+Indexes:
+    "temporal_fk_rng2rng_pk" PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+Foreign-key constraints:
+    "temporal_fk_rng2rng_fk" FOREIGN KEY (parent_id, PERIOD valid_at) REFERENCES temporal_rng(id, PERIOD valid_at)
+
 DROP TABLE temporal_fk_rng2rng;
 -- with mismatched PERIOD columns:
 -- (parent_id, PERIOD valid_at) REFERENCES (id, valid_at)
@@ -2669,6 +2923,1171 @@ SELECT * FROM temporal_fk2_mltrng2mltrng WHERE id = '[200,201)' ORDER BY id, val
  [200,201) | {[2020-01-01,2021-01-01)} | [8,9)      | [8,9)
 (2 rows)
 
+--
+-- test FOREIGN KEY, PERIOD references PERIOD
+--
+-- test table setup
+DROP TABLE temporal_per;
+CREATE TABLE temporal_per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	PERIOD FOR valid_at (valid_from, valid_til)
+);
+ALTER TABLE temporal_per
+	ADD CONSTRAINT temporal_per_pk
+	PRIMARY KEY (id, valid_at WITHOUT OVERLAPS);
+-- Can't create a FK with a mismatched range type
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from int,
+	valid_til int,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk2 PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk2 FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+ERROR:  foreign key constraint "temporal_fk_per2per_fk2" cannot be implemented
+DETAIL:  Key columns "valid_at" and "valid_at" are of incompatible types: int4range and daterange.
+-- works: PERIOD for both referenced and referencing
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+\d temporal_fk_per2per
+           Table "public.temporal_fk_per2per"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           | not null | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+ parent_id  | int4range |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal_fk_per2per_pk" PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal_fk_per2per_valid_at_check" CHECK (valid_from < valid_til)
+Foreign-key constraints:
+    "temporal_fk_per2per_fk" FOREIGN KEY (parent_id, PERIOD valid_at) REFERENCES temporal_per(id, PERIOD valid_at)
+
+DROP TABLE temporal_fk_per2per;
+-- with mismatched PERIOD columns:
+-- (parent_id, PERIOD valid_at) REFERENCES (id, valid_at)
+-- REFERENCES part should specify PERIOD
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, valid_at)
+);
+ERROR:  foreign key uses PERIOD on the referencing table but not the referenced table
+-- (parent_id, valid_at) REFERENCES (id, PERIOD valid_at)
+-- FOREIGN KEY part should specify PERIOD
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+ERROR:  foreign key uses PERIOD on the referenced table but not the referencing table
+-- (parent_id, valid_at) REFERENCES [implicit]
+-- FOREIGN KEY part should specify PERIOD
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, valid_at)
+		REFERENCES temporal_per
+);
+ERROR:  number of referencing and referenced columns for foreign key disagree
+-- (parent_id, PERIOD valid_at) REFERENCES (id)
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id)
+);
+ERROR:  foreign key uses PERIOD on the referencing table but not the referenced table
+-- (parent_id) REFERENCES (id, PERIOD valid_at)
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+ERROR:  foreign key uses PERIOD on the referenced table but not the referencing table
+-- with inferred PK on the referenced table:
+-- (This is not permitted by the SQL standard. See 11.8 syntax rule 4b.)
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per
+);
+ERROR:  foreign key uses PERIOD on the referencing table but not the referenced table
+-- (parent_id) REFERENCES [implicit]
+-- This finds the PK (omitting the WITHOUT OVERLAPS element),
+-- but it's not a b-tree index, so it fails anyway.
+-- Anyway it must fail because the two sides have a different definition of "unique".
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id)
+		REFERENCES temporal_per
+);
+ERROR:  only b-tree indexes are supported for foreign keys
+-- should fail because of duplicate referenced columns:
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD parent_id)
+		REFERENCES temporal_per (id, PERIOD id)
+);
+ERROR:  foreign key referenced-columns list must not contain duplicates
+-- Two scalar columns
+DROP TABLE temporal_per2;
+CREATE TABLE temporal_per2 (
+	id1 int4range,
+	id2 int4range,
+	valid_from date,
+	valid_til date,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_per2_pk PRIMARY KEY (id1, id2, valid_at WITHOUT OVERLAPS)
+);
+CREATE TABLE temporal_fk2_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id1 int4range,
+	parent_id2 int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk2_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk2_per2per_fk FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+);
+\d temporal_fk2_per2per
+           Table "public.temporal_fk2_per2per"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           | not null | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+ parent_id1 | int4range |           |          | 
+ parent_id2 | int4range |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal_fk2_per2per_pk" PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal_fk2_per2per_valid_at_check" CHECK (valid_from < valid_til)
+Foreign-key constraints:
+    "temporal_fk2_per2per_fk" FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at) REFERENCES temporal_per2(id1, id2, PERIOD valid_at)
+
+DROP TABLE temporal_fk2_per2per;
+--
+-- test ALTER TABLE ADD CONSTRAINT
+--
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+-- Two scalar columns:
+CREATE TABLE temporal_fk2_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id1 int4range,
+	parent_id2 int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk2_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+ALTER TABLE temporal_fk2_per2per
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+	FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+	REFERENCES temporal_per2 (id1, id2, PERIOD valid_at);
+\d temporal_fk2_per2per
+           Table "public.temporal_fk2_per2per"
+   Column   |   Type    | Collation | Nullable | Default 
+------------+-----------+-----------+----------+---------
+ id         | int4range |           | not null | 
+ valid_from | date      |           |          | 
+ valid_til  | date      |           |          | 
+ parent_id1 | int4range |           |          | 
+ parent_id2 | int4range |           |          | 
+Periods:
+    valid_at (valid_from, valid_til)
+Indexes:
+    "temporal_fk2_per2per_pk" PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+Check constraints:
+    "temporal_fk2_per2per_valid_at_check" CHECK (valid_from < valid_til)
+Foreign-key constraints:
+    "temporal_fk2_per2per_fk" FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at) REFERENCES temporal_per2(id1, id2, PERIOD valid_at)
+
+-- should fail because of duplicate referenced columns:
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk2
+	FOREIGN KEY (parent_id, PERIOD parent_id)
+	REFERENCES temporal_per (id, PERIOD id);
+ERROR:  foreign key referenced-columns list must not contain duplicates
+--
+-- test with rows already
+--
+DELETE FROM temporal_fk_per2per;
+DELETE FROM temporal_per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[1,1]', '2018-01-02', '2018-02-03'),
+  ('[1,1]', '2018-03-03', '2018-04-04'),
+  ('[2,2]', '2018-01-01', '2018-01-05'),
+  ('[3,3]', '2018-01-01', NULL);
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[1,1]', '2018-01-02', '2018-02-01', '[1,1]');
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[2,2]', '2018-01-02', '2018-04-01', '[1,1]');
+-- should fail:
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+ERROR:  insert or update on table "temporal_fk_per2per" violates foreign key constraint "temporal_fk_per2per_fk"
+DETAIL:  Key (parent_id, valid_at)=([1,2), [2018-01-02,2018-04-01)) is not present in table "temporal_per".
+-- okay again:
+DELETE FROM temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+--
+-- test pg_get_constraintdef
+--
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_fk_per2per_fk';
+                                 pg_get_constraintdef                                  
+---------------------------------------------------------------------------------------
+ FOREIGN KEY (parent_id, PERIOD valid_at) REFERENCES temporal_per(id, PERIOD valid_at)
+(1 row)
+
+--
+-- test FK referencing inserts
+--
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[1,1]', '2018-01-02', '2018-02-01', '[1,1]');
+-- should fail:
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[2,2]', '2018-01-02', '2018-04-01', '[1,1]');
+ERROR:  insert or update on table "temporal_fk_per2per" violates foreign key constraint "temporal_fk_per2per_fk"
+DETAIL:  Key (parent_id, valid_at)=([1,2), [2018-01-02,2018-04-01)) is not present in table "temporal_per".
+-- now it should work:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[1,1]', '2018-02-03', '2018-03-03');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[2,2]', '2018-01-02', '2018-04-01', '[1,1]');
+--
+-- test FK referencing updates
+--
+UPDATE temporal_fk_per2per SET valid_from = '2018-01-02', valid_til = '2018-03-01' WHERE id = '[1,1]';
+-- should fail:
+UPDATE temporal_fk_per2per SET valid_from = '2018-01-02', valid_til = '2018-05-01' WHERE id = '[1,1]';
+ERROR:  insert or update on table "temporal_fk_per2per" violates foreign key constraint "temporal_fk_per2per_fk"
+DETAIL:  Key (parent_id, valid_at)=([1,2), [2018-01-02,2018-05-01)) is not present in table "temporal_per".
+UPDATE temporal_fk_per2per SET parent_id = '[8,8]' WHERE id = '[1,1]';
+ERROR:  insert or update on table "temporal_fk_per2per" violates foreign key constraint "temporal_fk_per2per_fk"
+DETAIL:  Key (parent_id, valid_at)=([8,9), [2018-01-02,2018-03-01)) is not present in table "temporal_per".
+-- ALTER FK DEFERRABLE
+BEGIN;
+  INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+    ('[5,5]', '2018-01-01', '2018-02-01'),
+    ('[5,5]', '2018-02-01', '2018-03-01');
+  INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES
+    ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+  ALTER TABLE temporal_fk_per2per
+    ALTER CONSTRAINT temporal_fk_per2per_fk
+    DEFERRABLE INITIALLY DEFERRED;
+  DELETE FROM temporal_per WHERE id = '[5,5]'; --should not fail yet.
+COMMIT; -- should fail here.
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-01,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+--
+-- test FK parent updates NO ACTION
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+-- a PK update that succeeds because the numeric id isn't referenced:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01' WHERE id = '[5,5]';
+-- a PK update that succeeds even though the numeric id is referenced because the range isn't:
+DELETE FROM temporal_per WHERE id = '[5,5]';
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+UPDATE temporal_per SET valid_from = '2016-02-01', valid_til = '2016-03-01'
+WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK update that fails because both are referenced:
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-01,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+-- changing the scalar part fails:
+UPDATE temporal_per SET id = '[7,7]'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-01,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+-- changing an unreferenced part is okay:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+-- changing just a part fails:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-03,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  
+-------+------------+------------
+ [5,6) | 2016-02-01 | 2016-03-01
+ [5,6) | 2018-01-01 | 2018-01-02
+ [5,6) | 2018-01-03 | 2018-02-01
+ [7,8) | 2018-01-02 | 2018-01-03
+(4 rows)
+
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  | parent_id 
+-------+------------+------------+-----------
+ [3,4) | 2018-01-05 | 2018-01-10 | [5,6)
+(1 row)
+
+-- then delete the objecting FK record and the same PK update succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+--
+-- test FK parent updates RESTRICT
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at)
+	ON UPDATE RESTRICT;
+-- a PK update that succeeds because the numeric id isn't referenced:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01' WHERE id = '[5,5]';
+-- a PK update that succeeds even though the numeric id is referenced because the range isn't:
+DELETE FROM temporal_per WHERE id = '[5,5]';
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+UPDATE temporal_per SET valid_from = '2016-02-01', valid_til = '2016-03-01'
+WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK update that fails because both are referenced:
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-01,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+-- changing the scalar part fails:
+UPDATE temporal_per SET id = '[7,7]'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-01,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+-- changing an unreferenced part is okay:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+-- changing just a part fails:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-03,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  
+-------+------------+------------
+ [5,6) | 2016-02-01 | 2016-03-01
+ [5,6) | 2018-01-01 | 2018-01-02
+ [5,6) | 2018-01-03 | 2018-02-01
+ [7,8) | 2018-01-02 | 2018-01-03
+(4 rows)
+
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  | parent_id 
+-------+------------+------------+-----------
+ [3,4) | 2018-01-05 | 2018-01-10 | [5,6)
+(1 row)
+
+-- then delete the objecting FK record and the same PK update succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+--
+-- test FK parent deletes NO ACTION
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+-- a PK delete that succeeds because the numeric id isn't referenced:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+DELETE FROM temporal_per WHERE id = '[5,5]';
+-- a PK delete that succeeds even though the numeric id is referenced because the range isn't:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK delete that fails because both are referenced:
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-01,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+-- deleting an unreferenced part is okay:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+WHERE id = '[5,5]';
+-- deleting just a part fails:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+WHERE id = '[5,5]';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-03,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  
+-------+------------+------------
+ [5,6) | 2018-01-01 | 2018-01-02
+ [5,6) | 2018-01-03 | 2018-02-01
+(2 rows)
+
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  | parent_id 
+-------+------------+------------+-----------
+ [3,4) | 2018-01-05 | 2018-01-10 | [5,6)
+(1 row)
+
+-- then delete the objecting FK record and the same PK delete succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+--
+-- test FK parent deletes RESTRICT
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at)
+	ON DELETE RESTRICT;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+DELETE FROM temporal_per WHERE id = '[5,5]';
+-- a PK delete that succeeds even though the numeric id is referenced because the range isn't:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK delete that fails because both are referenced:
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-01,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+-- deleting an unreferenced part is okay:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+WHERE id = '[5,5]';
+-- deleting just a part fails:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+WHERE id = '[5,5]';
+ERROR:  update or delete on table "temporal_per" violates foreign key constraint "temporal_fk_per2per_fk" on table "temporal_fk_per2per"
+DETAIL:  Key (id, valid_at)=([5,6), [2018-01-03,2018-02-01)) is still referenced from table "temporal_fk_per2per".
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  
+-------+------------+------------
+ [5,6) | 2018-01-01 | 2018-01-02
+ [5,6) | 2018-01-03 | 2018-02-01
+(2 rows)
+
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+  id   | valid_from | valid_til  | parent_id 
+-------+------------+------------+-----------
+ [3,4) | 2018-01-05 | 2018-01-10 | [5,6)
+(1 row)
+
+-- then delete the objecting FK record and the same PK delete succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+--
+-- per2per test ON UPDATE/DELETE options
+--
+-- TOC:
+-- parent updates CASCADE
+-- parent deletes CASCADE
+-- parent updates SET NULL
+-- parent deletes SET NULL
+-- parent updates SET DEFAULT
+-- parent deletes SET DEFAULT
+-- parent updates CASCADE (two scalar cols)
+-- parent deletes CASCADE (two scalar cols)
+-- parent updates SET NULL (two scalar cols)
+-- parent deletes SET NULL (two scalar cols)
+-- parent deletes SET NULL (two scalar cols, SET NULL subset)
+-- parent updates SET DEFAULT (two scalar cols)
+-- parent deletes SET DEFAULT (two scalar cols)
+-- parent deletes SET DEFAULT (two scalar cols, SET DEFAULT subset)
+--
+-- test FK parent updates CASCADE
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk,
+	ADD CONSTRAINT temporal_fk_per2per_fk
+		FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+		ON DELETE CASCADE ON UPDATE CASCADE;
+-- leftovers on both sides:
+UPDATE temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [7,8)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)
+(3 rows)
+
+-- non-FPO update:
+UPDATE temporal_per SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [7,8)
+ [100,101) | 2019-01-01 | 2020-01-01 | [7,8)
+ [100,101) | 2020-01-01 | 2021-01-01 | [7,8)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+UPDATE temporal_per SET id = '[9,9]' WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [200,201) | 2018-01-01 | 2020-01-01 | [9,10)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes CASCADE
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)
+(2 rows)
+
+-- non-FPO delete:
+DELETE FROM temporal_per WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+ id | valid_from | valid_til | parent_id 
+----+------------+-----------+-----------
+(0 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+DELETE FROM temporal_per WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)
+(1 row)
+
+--
+-- test FK parent updates SET NULL
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk,
+	ADD CONSTRAINT temporal_fk_per2per_fk
+		FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+		ON DELETE SET NULL ON UPDATE SET NULL;
+-- leftovers on both sides:
+UPDATE temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | 
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)
+(3 rows)
+
+-- non-FPO update:
+UPDATE temporal_per SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | 
+ [100,101) | 2019-01-01 | 2020-01-01 | 
+ [100,101) | 2020-01-01 | 2021-01-01 | 
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+UPDATE temporal_per SET id = '[9,9]' WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [200,201) | 2018-01-01 | 2020-01-01 | 
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes SET NULL
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | 
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)
+(3 rows)
+
+-- non-FPO delete:
+DELETE FROM temporal_per WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | 
+ [100,101) | 2019-01-01 | 2020-01-01 | 
+ [100,101) | 2020-01-01 | 2021-01-01 | 
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+DELETE FROM temporal_per WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [200,201) | 2018-01-01 | 2020-01-01 | 
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)
+(2 rows)
+
+--
+-- test FK parent updates SET DEFAULT
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[-1,-1]', null, null);
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+ALTER TABLE temporal_fk_per2per
+  ALTER COLUMN parent_id SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk_per2per_fk,
+	ADD CONSTRAINT temporal_fk_per2per_fk
+		FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+		ON DELETE SET DEFAULT ON UPDATE SET DEFAULT;
+-- leftovers on both sides:
+UPDATE temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)
+(3 rows)
+
+-- non-FPO update:
+UPDATE temporal_per SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [-1,0)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [-1,0)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+UPDATE temporal_per SET id = '[9,9]' WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [200,201) | 2018-01-01 | 2020-01-01 | [-1,0)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes SET DEFAULT
+--
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[-1,-1]', null, null);
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)
+(3 rows)
+
+-- non-FPO update:
+DELETE FROM temporal_per WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [100,101) | 2018-01-01 | 2019-01-01 | [-1,0)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [-1,0)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+DELETE FROM temporal_per WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id 
+-----------+------------+------------+-----------
+ [200,201) | 2018-01-01 | 2020-01-01 | [-1,0)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)
+(2 rows)
+
+--
+-- test FK parent updates CASCADE (two scalar cols)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE CASCADE ON UPDATE CASCADE;
+-- leftovers on both sides:
+UPDATE temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [7,8)      | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(3 rows)
+
+-- non-FPO update:
+UPDATE temporal_per2 SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [7,8)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [7,8)      | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 | [7,8)      | [6,7)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+UPDATE temporal_per2 SET id1 = '[9,9]' WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2018-01-01 | 2020-01-01 | [9,10)     | [8,9)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes CASCADE (two scalar cols)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(2 rows)
+
+-- non-FPO delete:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+ id | valid_from | valid_til | parent_id1 | parent_id2 
+----+------------+-----------+------------+------------
+(0 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(1 row)
+
+--
+-- test FK parent updates SET NULL (two scalar cols)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET NULL ON UPDATE SET NULL;
+-- leftovers on both sides:
+UPDATE temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 |            | 
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(3 rows)
+
+-- non-FPO update:
+UPDATE temporal_per2 SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 |            | 
+ [100,101) | 2019-01-01 | 2020-01-01 |            | 
+ [100,101) | 2020-01-01 | 2021-01-01 |            | 
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+UPDATE temporal_per2 SET id1 = '[9,9]' WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2018-01-01 | 2020-01-01 |            | 
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes SET NULL (two scalar cols)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 |            | 
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(3 rows)
+
+-- non-FPO delete:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 |            | 
+ [100,101) | 2019-01-01 | 2020-01-01 |            | 
+ [100,101) | 2020-01-01 | 2021-01-01 |            | 
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2018-01-01 | 2020-01-01 |            | 
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes SET NULL (two scalar cols, SET NULL subset)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- fails because you can't set the PERIOD column:
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET NULL (valid_at) ON UPDATE SET NULL;
+ERROR:  column "valid_at" referenced in ON DELETE SET action cannot be PERIOD
+-- ok:
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET NULL (parent_id1) ON UPDATE SET NULL;
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 |            | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(3 rows)
+
+-- non-FPO delete:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 |            | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 |            | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 |            | [6,7)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2018-01-01 | 2020-01-01 |            | [8,9)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(2 rows)
+
+--
+-- test FK parent updates SET DEFAULT (two scalar cols)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[-1,-1]', null, null);
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+ALTER TABLE temporal_fk2_per2per
+  ALTER COLUMN parent_id1 SET DEFAULT '[-1,-1]',
+  ALTER COLUMN parent_id2 SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET DEFAULT ON UPDATE SET DEFAULT;
+-- leftovers on both sides:
+UPDATE temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id1 = '[7,7]', id2 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)     | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(3 rows)
+
+-- non-FPO update:
+UPDATE temporal_per2 SET id1 = '[7,7]', id2 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [-1,0)     | [-1,0)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)     | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [-1,0)     | [-1,0)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+UPDATE temporal_per2 SET id1 = '[9,9]', id2 = '[9,9]' WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2018-01-01 | 2020-01-01 | [-1,0)     | [-1,0)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes SET DEFAULT (two scalar cols)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[-1,-1]', null, null);
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)     | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(3 rows)
+
+-- non-FPO update:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [-1,0)     | [-1,0)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)     | [-1,0)
+ [100,101) | 2020-01-01 | 2021-01-01 | [-1,0)     | [-1,0)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2018-01-01 | 2020-01-01 | [-1,0)     | [-1,0)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(2 rows)
+
+--
+-- test FK parent deletes SET DEFAULT (two scalar cols, SET DEFAULT subset)
+--
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[6,6]', null, null);
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- fails because you can't set the PERIOD column:
+ALTER TABLE temporal_fk2_per2per
+  ALTER COLUMN parent_id1 SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET DEFAULT (valid_at) ON UPDATE SET DEFAULT;
+ERROR:  column "valid_at" referenced in ON DELETE SET action cannot be PERIOD
+-- ok:
+ALTER TABLE temporal_fk2_per2per
+  ALTER COLUMN parent_id1 SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET DEFAULT (parent_id1) ON UPDATE SET DEFAULT;
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [6,7)      | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)     | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 | [6,7)      | [6,7)
+(3 rows)
+
+-- non-FPO update:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [100,101) | 2018-01-01 | 2019-01-01 | [-1,0)     | [6,7)
+ [100,101) | 2019-01-01 | 2020-01-01 | [-1,0)     | [6,7)
+ [100,101) | 2020-01-01 | 2021-01-01 | [-1,0)     | [6,7)
+(3 rows)
+
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[8,8]', null, null);
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+    id     | valid_from | valid_til  | parent_id1 | parent_id2 
+-----------+------------+------------+------------+------------
+ [200,201) | 2018-01-01 | 2020-01-01 | [-1,0)     | [8,9)
+ [200,201) | 2020-01-01 | 2021-01-01 | [8,9)      | [8,9)
+(2 rows)
+
 -- FK with a custom range type
 CREATE TYPE mydaterange AS range(subtype=date);
 CREATE TABLE temporal_rng3 (
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 4fd7f3d0c73..6685cc357df 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -43,7 +43,7 @@ test: copy copyselect copydml insert insert_conflict
 # Note: many of the tests in later groups depend on create_index
 # ----------
 test: create_function_c create_misc create_operator create_procedure create_table create_type create_schema
-test: create_index create_index_spgist create_view index_including index_including_gist
+test: create_index create_index_spgist create_view index_including index_including_gist periods
 
 # ----------
 # Another group of parallel tests
diff --git a/src/test/regress/sql/for_portion_of.sql b/src/test/regress/sql/for_portion_of.sql
index e802b5c67ff..e25215a3fd5 100644
--- a/src/test/regress/sql/for_portion_of.sql
+++ b/src/test/regress/sql/for_portion_of.sql
@@ -423,6 +423,38 @@ SELECT * FROM for_portion_of_test2 ORDER BY id, valid_at;
 
 DROP TABLE for_portion_of_test2;
 
+-- Test with PERIODs
+
+CREATE TABLE for_portion_of_test2 (
+  id int4range NOT NULL,
+  valid_from date,
+  valid_til date,
+  name text NOT NULL,
+  PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT for_portion_of_test2_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+INSERT INTO for_portion_of_test2
+VALUES
+('[1,2)', '2018-01-02', '2018-02-03', 'one'),
+('[1,2)', '2018-02-04', '2018-03-03', 'one'),
+('[1,2)', '2018-03-03', '2018-04-04', 'one'),
+('[2,3)', '2018-01-01', '2018-05-01', 'two'),
+('[3,4)', '2018-01-01', null, 'three');
+;
+
+UPDATE for_portion_of_test2
+FOR PORTION OF valid_at FROM '2018-01-10' TO '2018-02-10'
+SET name = 'one^1'
+WHERE id = '[1,2)';
+
+DELETE FROM for_portion_of_test2
+FOR PORTION OF valid_at FROM '2018-01-15' TO '2018-02-15'
+WHERE id = '[2,3)';
+
+SELECT * FROM for_portion_of_test2 ORDER BY id, valid_at;
+
+DROP TABLE for_portion_of_test2;
+
 -- Test with a custom range type
 
 CREATE TYPE mydaterange AS range(subtype=date);
diff --git a/src/test/regress/sql/periods.sql b/src/test/regress/sql/periods.sql
new file mode 100644
index 00000000000..5d39712d2b4
--- /dev/null
+++ b/src/test/regress/sql/periods.sql
@@ -0,0 +1,178 @@
+/* System periods are not implemented */
+create table pt (id integer, ds date, de date, period for system_time (ds, de));
+
+/* Periods must specify actual columns */
+create table pt (id integer, ds date, de date, period for p (bogus, de));
+create table pt (id integer, ds date, de date, period for p (ds, bogus));
+
+/* Data types must match exactly */
+create table pt (id integer, ds date, de timestamp, period for p (ds, de));
+create table pt (id integer, ds text collate "C", de text collate "POSIX", period for p (ds, de));
+
+/* Periods must have a default BTree operator class */
+create table pt (id integer, ds xml, de xml, period for p (ds, de));
+
+/* Period and column names are in the same namespace */
+create table pt (id integer, ds date, de date, period for ctid (ds, de));
+create table pt (id integer, ds date, de date, period for id (ds, de));
+
+/* Period name can't be given more than once */
+create table pt (id integer, ds date, de date, period for p (ds, de), period for p (ds, de));
+
+/* Now make one that works */
+create table pt (id integer, ds date, de date, period for p (ds, de));
+
+/* SELECT * excludes the PERIOD */
+insert into pt values (1, '2000-01-01', '2001-01-01');
+select * from pt;
+
+/* You can get it if you want */
+select *, p from pt;
+
+/* Two are okay */
+create table pt2 (id integer, ds date, de date, period for p1 (ds, de), period for p2 (ds, de));
+drop table pt2;
+
+/* Skip creating GENERATED column: works */
+create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored, period for p (ds, de) with (colexists = true));
+\d pt2
+drop table pt2;
+/* Skip creating GENERATED column: fails because the col isn't there */
+create table pt2 (id integer, ds date, de date, period for p (ds, de) with (colexists = true));
+/* Skip creating GENERATED column: fails because the option has an invalid value */
+create table pt2 (id integer, ds date, de date, period for p (ds, de) with (colexists = 'whatever'));
+/* Skip creating GENERATED column: fails because the column is not NOT NULL */
+create table pt2 (id integer, ds date, de date, p daterange generated always as (daterange(ds, de)) stored, period for p (ds, de) with (colexists = true));
+/* Skip creating GENERATED column: fails because the column is not GENERATED */
+create table pt2 (id integer, ds date, de date, p daterange not null, period for p (ds, de) with (colexists = true));
+/* Skip creating GENERATED column: fails because the column is GENERATED but with the wrong expression */
+-- TODO:
+-- create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(de, ds)) stored, period for p (ds, de) with (colexists = true));
+/* Skip creating GENERATED column: fails because the column is the wrong type */
+create table pt2 (id integer, ds date, de date, p tsrange not null generated always as (tsrange(ds, de)) stored, period for p (ds, de) with (colexists = true));
+/* Skip creating GENERATED column: fails because the column is inherited */
+create table pt2parent (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+create table pt2 (period for p (ds, de) with (colexists = true)) inherits (pt2parent);
+drop table pt2parent;
+
+
+/*
+ * ALTER TABLE tests
+ */
+alter table pt drop period for p;
+alter table pt add period for system_time (ds, de);
+alter table pt add period for p (ds, de);
+
+/* Adding a second one */
+create table pt2 (id integer, ds date, de date, period for p1 (ds, de));
+alter table pt2 add period for p2 (ds, de);
+drop table pt2;
+
+/* Can't drop its columns */
+alter table pt drop column ds;
+alter table pt drop column de;
+
+/* Can't change the data types */
+alter table pt alter column ds type timestamp;
+alter table pt alter column ds type timestamp;
+
+/* column/period namespace conflicts */
+alter table pt add column p integer;
+alter table pt rename column id to p;
+alter table pt add period for tableoid (ds, de);
+alter table pt add period for "........pg.dropped.4........" (ds, de);
+
+/* adding columns and the period at the same time */
+create table pt2 (id integer);
+alter table pt2 add column ds date, add column de date, add period for p (ds, de);
+drop table pt2;
+
+/* Ambiguous range types raise an error */
+create type mydaterange as range(subtype=date);
+create table pt2 (id int, ds date, de date, period for p (ds, de));
+
+/* You can give an explicit range type */
+create table pt2 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'mydaterange'));
+drop type mydaterange;
+drop type mydaterange cascade;
+drop table pt2;
+create table pt2 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'daterange'));
+
+/* Range type is not found */
+create table pt3 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'notarange'));
+
+/* Range type is the wrong type */
+create table pt3 (id int, ds date, de date, period for p (ds, de) with (rangetype = 'tstzrange'));
+drop table pt2;
+
+/* Skip creating GENERATED column: works */
+create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+\d pt2
+drop table pt2;
+/* Skip creating GENERATED column: fails because the col isn't there */
+create table pt2 (id integer, ds date, de date);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+drop table pt2;
+/* Skip creating GENERATED column: fails because the option has an invalid value */
+create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = 'whatever');
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is not NOT NULL */
+create table pt2 (id integer, ds date, de date, p daterange generated always as (daterange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is not GENERATED */
+create table pt2 (id integer, ds date, de date, p daterange not null);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is GENERATED but with the wrong expression */
+-- TODO:
+-- create table pt2 (id integer, ds date, de date, p daterange not null generated always as (daterange(de, ds)) stored);
+-- alter table pt2 add period for p (ds, de) with (colexists = true);
+/* Skip creating GENERATED column: fails because the column is the wrong type */
+create table pt2 (id integer, ds date, de date, p tsrange not null generated always as (tsrange(ds, de)) stored);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+drop table pt2;
+/* Skip creating GENERATED column: fails because the column is inherited */
+create table pt2parent (id integer, ds date, de date, p daterange not null generated always as (daterange(ds, de)) stored);
+create table pt2 () inherits (pt2parent);
+alter table pt2 add period for p (ds, de) with (colexists = true);
+drop table pt2;
+drop table pt2parent;
+
+/* CREATE TABLE (LIKE ...) */
+
+/* Periods are not copied by LIKE, so their columns aren't either */
+create table pt2 (like pt);
+\d pt2
+drop table pt2;
+
+/* Can add a period referring to LIKE'd columns */
+create table not_p (id integer, ds date, de date);
+create table pt2 (like not_p, period for p (ds, de));
+\d pt2
+drop table pt2;
+
+/* Can add a period with the same name */
+create table pt2 (like pt, period for p (ds, de));
+\d pt2
+drop table pt2;
+
+/* Can add a period with a different name */
+create table pt2 (like pt, period for p2 (ds, de));
+\d pt2
+drop table pt2;
+
+/* Can't add a period whose name conflicts with a LIKE'd column */
+create table pt2 (like pt, period for id (ds, de));
+
+/* CREATE TALBE INHERITS */
+
+/* Can't inherit from a table with a period */
+create table pt2 (name text) inherits (pt);
+
+/* Can't inherit with a period */
+create table pt2 (d2s date, d2e date, period for p (d2s, d2e)) inherits (not_p);
+
+drop table not_p;
diff --git a/src/test/regress/sql/without_overlaps.sql b/src/test/regress/sql/without_overlaps.sql
index e617bd29417..cd596ae11e9 100644
--- a/src/test/regress/sql/without_overlaps.sql
+++ b/src/test/regress/sql/without_overlaps.sql
@@ -58,6 +58,31 @@ CREATE TABLE temporal_rng2 (
 SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_rng2_pk';
 SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_rng2_pk';
 
+-- PK with one column plus a PERIOD:
+CREATE TABLE temporal_per (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per_pk';
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per_pk';
+
+-- PK with two columns plus a PERIOD:
+CREATE TABLE temporal_per2 (
+  id1 int4range,
+  id2 int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per2_pk PRIMARY KEY (id1, id2, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per2
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per2_pk';
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per2_pk';
+
 -- PK with a custom range type:
 CREATE TYPE textrange2 AS range (subtype=text, collation="C");
 CREATE TABLE temporal_rng3 (
@@ -135,6 +160,33 @@ SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_rn
 SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_rng3_uq';
 DROP TABLE temporal_rng3;
 
+-- UNIQUE with one column plus a PERIOD:
+CREATE TABLE temporal_per3 (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per3_uq UNIQUE (id, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per3
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+DROP TABLE temporal_per3;
+
+-- UNIQUE with two columns plus a PERIOD:
+CREATE TABLE temporal_per3 (
+  id1 int4range,
+  id2 int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til),
+  CONSTRAINT temporal_per3_uq UNIQUE (id1, id2, valid_at WITHOUT OVERLAPS)
+);
+\d temporal_per3
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+SELECT pg_get_indexdef(conindid, 0, true) FROM pg_constraint WHERE conname = 'temporal_per3_uq';
+DROP TABLE temporal_per3;
+
 -- UNIQUE with a custom range type:
 CREATE TYPE textrange2 AS range (subtype=text, collation="C");
 CREATE TABLE temporal_rng3 (
@@ -212,6 +264,58 @@ ALTER TABLE temporal3
 	UNIQUE (id, valid_at WITHOUT OVERLAPS);
 DROP TABLE temporal3;
 
+-- PRIMARY KEY with PERIOD already there
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til)
+);
+ALTER TABLE temporal3
+  ADD CONSTRAINT temporal3_pk
+  PRIMARY KEY (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+DROP TABLE temporal3;
+
+-- PRIMARY KEY with PERIOD too
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date
+);
+ALTER TABLE temporal3
+  ADD PERIOD FOR valid_at (valid_from, valid_til),
+  ADD CONSTRAINT temporal3_pk
+  PRIMARY KEY (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+DROP TABLE temporal3;
+
+-- UNIQUE with PERIOD already there
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date,
+  PERIOD FOR valid_at (valid_from, valid_til)
+);
+ALTER TABLE temporal3
+  ADD CONSTRAINT temporal3_uq
+  UNIQUE (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+DROP TABLE temporal3;
+
+-- UNIQUE with PERIOD too
+CREATE TABLE temporal3 (
+  id int4range,
+  valid_from date,
+  valid_til date
+);
+ALTER TABLE temporal3
+  ADD PERIOD FOR valid_at (valid_from, valid_til),
+  ADD CONSTRAINT temporal3_uq
+  UNIQUE (id, valid_at WITHOUT OVERLAPS);
+\d temporal3
+DROP TABLE temporal3;
+
 --
 -- test PK inserts
 --
@@ -414,6 +518,7 @@ CREATE TABLE temporal_fk_rng2rng (
 	CONSTRAINT temporal_fk_rng2rng_fk FOREIGN KEY (parent_id, PERIOD valid_at)
 		REFERENCES temporal_rng (id, PERIOD valid_at)
 );
+\d temporal_fk_rng2rng
 DROP TABLE temporal_fk_rng2rng;
 
 -- with mismatched PERIOD columns:
@@ -1902,6 +2007,817 @@ INSERT INTO temporal_fk2_mltrng2mltrng (id, valid_at, parent_id1, parent_id2) VA
 DELETE FROM temporal_mltrng2 WHERE id1 = '[8,9)' AND valid_at @> '2019-01-01'::date;
 SELECT * FROM temporal_fk2_mltrng2mltrng WHERE id = '[200,201)' ORDER BY id, valid_at;
 
+--
+-- test FOREIGN KEY, PERIOD references PERIOD
+--
+
+-- test table setup
+DROP TABLE temporal_per;
+CREATE TABLE temporal_per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	PERIOD FOR valid_at (valid_from, valid_til)
+);
+ALTER TABLE temporal_per
+	ADD CONSTRAINT temporal_per_pk
+	PRIMARY KEY (id, valid_at WITHOUT OVERLAPS);
+
+-- Can't create a FK with a mismatched range type
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from int,
+	valid_til int,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk2 PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk2 FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+
+-- works: PERIOD for both referenced and referencing
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+\d temporal_fk_per2per
+DROP TABLE temporal_fk_per2per;
+
+-- with mismatched PERIOD columns:
+
+-- (parent_id, PERIOD valid_at) REFERENCES (id, valid_at)
+-- REFERENCES part should specify PERIOD
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, valid_at)
+);
+-- (parent_id, valid_at) REFERENCES (id, PERIOD valid_at)
+-- FOREIGN KEY part should specify PERIOD
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+-- (parent_id, valid_at) REFERENCES [implicit]
+-- FOREIGN KEY part should specify PERIOD
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, valid_at)
+		REFERENCES temporal_per
+);
+-- (parent_id, PERIOD valid_at) REFERENCES (id)
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id)
+);
+-- (parent_id) REFERENCES (id, PERIOD valid_at)
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+);
+
+-- with inferred PK on the referenced table:
+-- (This is not permitted by the SQL standard. See 11.8 syntax rule 4b.)
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per
+);
+-- (parent_id) REFERENCES [implicit]
+-- This finds the PK (omitting the WITHOUT OVERLAPS element),
+-- but it's not a b-tree index, so it fails anyway.
+-- Anyway it must fail because the two sides have a different definition of "unique".
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id)
+		REFERENCES temporal_per
+);
+
+-- should fail because of duplicate referenced columns:
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk_per2per_fk FOREIGN KEY (parent_id, PERIOD parent_id)
+		REFERENCES temporal_per (id, PERIOD id)
+);
+
+-- Two scalar columns
+DROP TABLE temporal_per2;
+CREATE TABLE temporal_per2 (
+	id1 int4range,
+	id2 int4range,
+	valid_from date,
+	valid_til date,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_per2_pk PRIMARY KEY (id1, id2, valid_at WITHOUT OVERLAPS)
+);
+
+CREATE TABLE temporal_fk2_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id1 int4range,
+	parent_id2 int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk2_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS),
+	CONSTRAINT temporal_fk2_per2per_fk FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+);
+\d temporal_fk2_per2per
+DROP TABLE temporal_fk2_per2per;
+
+--
+-- test ALTER TABLE ADD CONSTRAINT
+--
+
+CREATE TABLE temporal_fk_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+-- Two scalar columns:
+CREATE TABLE temporal_fk2_per2per (
+	id int4range,
+	valid_from date,
+	valid_til date,
+	parent_id1 int4range,
+	parent_id2 int4range,
+	PERIOD FOR valid_at (valid_from, valid_til),
+	CONSTRAINT temporal_fk2_per2per_pk PRIMARY KEY (id, valid_at WITHOUT OVERLAPS)
+);
+ALTER TABLE temporal_fk2_per2per
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+	FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+	REFERENCES temporal_per2 (id1, id2, PERIOD valid_at);
+\d temporal_fk2_per2per
+
+-- should fail because of duplicate referenced columns:
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk2
+	FOREIGN KEY (parent_id, PERIOD parent_id)
+	REFERENCES temporal_per (id, PERIOD id);
+
+--
+-- test with rows already
+--
+
+DELETE FROM temporal_fk_per2per;
+DELETE FROM temporal_per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[1,1]', '2018-01-02', '2018-02-03'),
+  ('[1,1]', '2018-03-03', '2018-04-04'),
+  ('[2,2]', '2018-01-01', '2018-01-05'),
+  ('[3,3]', '2018-01-01', NULL);
+
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[1,1]', '2018-01-02', '2018-02-01', '[1,1]');
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[2,2]', '2018-01-02', '2018-04-01', '[1,1]');
+-- should fail:
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+-- okay again:
+DELETE FROM temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+
+--
+-- test pg_get_constraintdef
+--
+
+SELECT pg_get_constraintdef(oid) FROM pg_constraint WHERE conname = 'temporal_fk_per2per_fk';
+
+--
+-- test FK referencing inserts
+--
+
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[1,1]', '2018-01-02', '2018-02-01', '[1,1]');
+-- should fail:
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[2,2]', '2018-01-02', '2018-04-01', '[1,1]');
+-- now it should work:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[1,1]', '2018-02-03', '2018-03-03');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[2,2]', '2018-01-02', '2018-04-01', '[1,1]');
+
+--
+-- test FK referencing updates
+--
+
+UPDATE temporal_fk_per2per SET valid_from = '2018-01-02', valid_til = '2018-03-01' WHERE id = '[1,1]';
+-- should fail:
+UPDATE temporal_fk_per2per SET valid_from = '2018-01-02', valid_til = '2018-05-01' WHERE id = '[1,1]';
+UPDATE temporal_fk_per2per SET parent_id = '[8,8]' WHERE id = '[1,1]';
+
+-- ALTER FK DEFERRABLE
+
+BEGIN;
+  INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+    ('[5,5]', '2018-01-01', '2018-02-01'),
+    ('[5,5]', '2018-02-01', '2018-03-01');
+  INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES
+    ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+  ALTER TABLE temporal_fk_per2per
+    ALTER CONSTRAINT temporal_fk_per2per_fk
+    DEFERRABLE INITIALLY DEFERRED;
+
+  DELETE FROM temporal_per WHERE id = '[5,5]'; --should not fail yet.
+COMMIT; -- should fail here.
+
+--
+-- test FK parent updates NO ACTION
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+-- a PK update that succeeds because the numeric id isn't referenced:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01' WHERE id = '[5,5]';
+-- a PK update that succeeds even though the numeric id is referenced because the range isn't:
+DELETE FROM temporal_per WHERE id = '[5,5]';
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+UPDATE temporal_per SET valid_from = '2016-02-01', valid_til = '2016-03-01'
+WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK update that fails because both are referenced:
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+-- changing the scalar part fails:
+UPDATE temporal_per SET id = '[7,7]'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+-- changing an unreferenced part is okay:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+-- changing just a part fails:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+-- then delete the objecting FK record and the same PK update succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+
+--
+-- test FK parent updates RESTRICT
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at)
+	ON UPDATE RESTRICT;
+-- a PK update that succeeds because the numeric id isn't referenced:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01' WHERE id = '[5,5]';
+-- a PK update that succeeds even though the numeric id is referenced because the range isn't:
+DELETE FROM temporal_per WHERE id = '[5,5]';
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+UPDATE temporal_per SET valid_from = '2016-02-01', valid_til = '2016-03-01'
+WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK update that fails because both are referenced:
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+-- changing the scalar part fails:
+UPDATE temporal_per SET id = '[7,7]'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+-- changing an unreferenced part is okay:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+-- changing just a part fails:
+UPDATE temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+SET id = '[7,7]'
+WHERE id = '[5,5]';
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+-- then delete the objecting FK record and the same PK update succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+UPDATE temporal_per SET valid_from = '2016-01-01', valid_til = '2016-02-01'
+WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+
+--
+-- test FK parent deletes NO ACTION
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at);
+-- a PK delete that succeeds because the numeric id isn't referenced:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+DELETE FROM temporal_per WHERE id = '[5,5]';
+-- a PK delete that succeeds even though the numeric id is referenced because the range isn't:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK delete that fails because both are referenced:
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+-- deleting an unreferenced part is okay:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+WHERE id = '[5,5]';
+-- deleting just a part fails:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+WHERE id = '[5,5]';
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+-- then delete the objecting FK record and the same PK delete succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+
+--
+-- test FK parent deletes RESTRICT
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk;
+ALTER TABLE temporal_fk_per2per
+	ADD CONSTRAINT temporal_fk_per2per_fk
+	FOREIGN KEY (parent_id, PERIOD valid_at)
+	REFERENCES temporal_per (id, PERIOD valid_at)
+	ON DELETE RESTRICT;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[5,5]', '2018-01-01', '2018-02-01');
+DELETE FROM temporal_per WHERE id = '[5,5]';
+-- a PK delete that succeeds even though the numeric id is referenced because the range isn't:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES
+  ('[5,5]', '2018-01-01', '2018-02-01'),
+  ('[5,5]', '2018-02-01', '2018-03-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[3,3]', '2018-01-05', '2018-01-10', '[5,5]');
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-02-01' AND valid_til = '2018-03-01';
+-- a PK delete that fails because both are referenced:
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+-- deleting an unreferenced part is okay:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-02' TO '2018-01-03'
+WHERE id = '[5,5]';
+-- deleting just a part fails:
+DELETE FROM temporal_per
+FOR PORTION OF valid_at FROM '2018-01-05' TO '2018-01-10'
+WHERE id = '[5,5]';
+SELECT * FROM temporal_per WHERE id in ('[5,5]', '[7,7]') ORDER BY id, valid_at;
+SELECT * FROM temporal_fk_per2per WHERE id in ('[3,3]') ORDER BY id, valid_at;
+-- then delete the objecting FK record and the same PK delete succeeds:
+DELETE FROM temporal_fk_per2per WHERE id = '[3,3]';
+DELETE FROM temporal_per WHERE id = '[5,5]' AND valid_from = '2018-01-01' AND valid_til = '2018-02-01';
+
+--
+-- per2per test ON UPDATE/DELETE options
+--
+-- TOC:
+-- parent updates CASCADE
+-- parent deletes CASCADE
+-- parent updates SET NULL
+-- parent deletes SET NULL
+-- parent updates SET DEFAULT
+-- parent deletes SET DEFAULT
+-- parent updates CASCADE (two scalar cols)
+-- parent deletes CASCADE (two scalar cols)
+-- parent updates SET NULL (two scalar cols)
+-- parent deletes SET NULL (two scalar cols)
+-- parent deletes SET NULL (two scalar cols, SET NULL subset)
+-- parent updates SET DEFAULT (two scalar cols)
+-- parent deletes SET DEFAULT (two scalar cols)
+-- parent deletes SET DEFAULT (two scalar cols, SET DEFAULT subset)
+
+--
+-- test FK parent updates CASCADE
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk,
+	ADD CONSTRAINT temporal_fk_per2per_fk
+		FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+		ON DELETE CASCADE ON UPDATE CASCADE;
+-- leftovers on both sides:
+UPDATE temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+UPDATE temporal_per SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+UPDATE temporal_per SET id = '[9,9]' WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes CASCADE
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO delete:
+DELETE FROM temporal_per WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+DELETE FROM temporal_per WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent updates SET NULL
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+ALTER TABLE temporal_fk_per2per
+	DROP CONSTRAINT temporal_fk_per2per_fk,
+	ADD CONSTRAINT temporal_fk_per2per_fk
+		FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+		ON DELETE SET NULL ON UPDATE SET NULL;
+-- leftovers on both sides:
+UPDATE temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+UPDATE temporal_per SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+UPDATE temporal_per SET id = '[9,9]' WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes SET NULL
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO delete:
+DELETE FROM temporal_per WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+DELETE FROM temporal_per WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent updates SET DEFAULT
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[-1,-1]', null, null);
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+ALTER TABLE temporal_fk_per2per
+  ALTER COLUMN parent_id SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk_per2per_fk,
+	ADD CONSTRAINT temporal_fk_per2per_fk
+		FOREIGN KEY (parent_id, PERIOD valid_at)
+		REFERENCES temporal_per (id, PERIOD valid_at)
+		ON DELETE SET DEFAULT ON UPDATE SET DEFAULT;
+-- leftovers on both sides:
+UPDATE temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+UPDATE temporal_per SET id = '[7,7]' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+UPDATE temporal_per SET id = '[9,9]' WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes SET DEFAULT
+--
+
+TRUNCATE temporal_per, temporal_fk_per2per;
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[-1,-1]', null, null);
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+DELETE FROM temporal_per WHERE id = '[6,6]';
+SELECT * FROM temporal_fk_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per (id, valid_from, valid_til) VALUES ('[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk_per2per (id, valid_from, valid_til, parent_id) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]');
+DELETE FROM temporal_per WHERE id = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent updates CASCADE (two scalar cols)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE CASCADE ON UPDATE CASCADE;
+-- leftovers on both sides:
+UPDATE temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+UPDATE temporal_per2 SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+UPDATE temporal_per2 SET id1 = '[9,9]' WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes CASCADE (two scalar cols)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO delete:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent updates SET NULL (two scalar cols)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET NULL ON UPDATE SET NULL;
+-- leftovers on both sides:
+UPDATE temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+UPDATE temporal_per2 SET id1 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+UPDATE temporal_per2 SET id1 = '[9,9]' WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes SET NULL (two scalar cols)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO delete:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes SET NULL (two scalar cols, SET NULL subset)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- fails because you can't set the PERIOD column:
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET NULL (valid_at) ON UPDATE SET NULL;
+-- ok:
+ALTER TABLE temporal_fk2_per2per
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET NULL (parent_id1) ON UPDATE SET NULL;
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO delete:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent updates SET DEFAULT (two scalar cols)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[-1,-1]', null, null);
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+ALTER TABLE temporal_fk2_per2per
+  ALTER COLUMN parent_id1 SET DEFAULT '[-1,-1]',
+  ALTER COLUMN parent_id2 SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET DEFAULT ON UPDATE SET DEFAULT;
+-- leftovers on both sides:
+UPDATE temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' SET id1 = '[7,7]', id2 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+UPDATE temporal_per2 SET id1 = '[7,7]', id2 = '[7,7]' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+UPDATE temporal_per2 SET id1 = '[9,9]', id2 = '[9,9]' WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes SET DEFAULT (two scalar cols)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[-1,-1]', null, null);
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
+--
+-- test FK parent deletes SET DEFAULT (two scalar cols, SET DEFAULT subset)
+--
+
+TRUNCATE temporal_per2, temporal_fk2_per2per;
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[6,6]', null, null);
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[6,6]', '[6,6]', '2018-01-01', '2021-01-01');
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[100,100]', '2018-01-01', '2021-01-01', '[6,6]', '[6,6]');
+-- fails because you can't set the PERIOD column:
+ALTER TABLE temporal_fk2_per2per
+  ALTER COLUMN parent_id1 SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET DEFAULT (valid_at) ON UPDATE SET DEFAULT;
+-- ok:
+ALTER TABLE temporal_fk2_per2per
+  ALTER COLUMN parent_id1 SET DEFAULT '[-1,-1]',
+	DROP CONSTRAINT temporal_fk2_per2per_fk,
+	ADD CONSTRAINT temporal_fk2_per2per_fk
+		FOREIGN KEY (parent_id1, parent_id2, PERIOD valid_at)
+		REFERENCES temporal_per2 (id1, id2, PERIOD valid_at)
+		ON DELETE SET DEFAULT (parent_id1) ON UPDATE SET DEFAULT;
+-- leftovers on both sides:
+DELETE FROM temporal_per2 FOR PORTION OF valid_at FROM '2019-01-01' TO '2020-01-01' WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- non-FPO update:
+DELETE FROM temporal_per2 WHERE id1 = '[6,6]';
+SELECT * FROM temporal_fk2_per2per WHERE id = '[100,100]' ORDER BY id, valid_at;
+-- FK across two referenced rows:
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2018-01-01', '2020-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[8,8]', '[8,8]', '2020-01-01', '2021-01-01');
+INSERT INTO temporal_per2 (id1, id2, valid_from, valid_til) VALUES ('[-1,-1]', '[8,8]', null, null);
+INSERT INTO temporal_fk2_per2per (id, valid_from, valid_til, parent_id1, parent_id2) VALUES ('[200,200]', '2018-01-01', '2021-01-01', '[8,8]', '[8,8]');
+DELETE FROM temporal_per2 WHERE id1 = '[8,8]' AND valid_at @> '2019-01-01'::date;
+SELECT * FROM temporal_fk2_per2per WHERE id = '[200,200]' ORDER BY id, valid_at;
+
 -- FK with a custom range type
 
 CREATE TYPE mydaterange AS range(subtype=date);
-- 
2.42.0

