From ba91ac0d9403f304d6c72683ca2c471e2c3c3ecc Mon Sep 17 00:00:00 2001 From: jian he Date: Thu, 3 Apr 2025 16:45:48 +0800 Subject: [PATCH v3 1/1] COPY materialized_view TO generally `COPY table TO` is faster than `COPY (query)`. since populated materialized view have physical storage, so this can use table_beginscan, table_endscan to scan a table. context: https://postgr.es/m/8967.1353167301@sss.pgh.pa.us context: https://www.postgresql.org/message-id/flat/20121116162558.90150%40gmx.com discussion: https://postgr.es/m/CACJufxHVxnyRYy67hiPePNCPwVBMzhTQ6FaL9_Te5On9udG=yg@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5533/ --- doc/src/sgml/ref/copy.sgml | 14 ++++++++------ src/backend/commands/copyto.c | 13 ++++++++----- src/test/regress/expected/copy.out | 11 +++++++++++ src/test/regress/sql/copy.sql | 8 ++++++++ 4 files changed, 35 insertions(+), 11 deletions(-) diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml index df093da97c5..c855e98f757 100644 --- a/doc/src/sgml/ref/copy.sgml +++ b/doc/src/sgml/ref/copy.sgml @@ -520,12 +520,14 @@ COPY count Notes - COPY TO can be used only with plain - tables, not views, and does not copy rows from child tables - or child partitions. For example, COPY table TO copies - the same rows as SELECT * FROM ONLY table. + COPY TO can be used with plain + tables and populated materialized views. + For example, + COPY table TO + copies the same rows as + SELECT * FROM ONLY table. + However it doesn't directly support other relation types, + such as partitioned tables, inheritance child tables, or views. The syntax COPY (SELECT * FROM table) TO ... can be used to dump all of the rows in an inheritance hierarchy, partitioned table, diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c index 84a3f3879a8..9233cbcecb4 100644 --- a/src/backend/commands/copyto.c +++ b/src/backend/commands/copyto.c @@ -653,11 +653,14 @@ BeginCopyTo(ParseState *pstate, RelationGetRelationName(rel)), errhint("Try the COPY (SELECT ...) TO variant."))); else if (rel->rd_rel->relkind == RELKIND_MATVIEW) - ereport(ERROR, - (errcode(ERRCODE_WRONG_OBJECT_TYPE), - errmsg("cannot copy from materialized view \"%s\"", - RelationGetRelationName(rel)), - errhint("Try the COPY (SELECT ...) TO variant."))); + { + if (!RelationIsPopulated(rel)) + ereport(ERROR, + errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot copy from unpopulated materialized view \"%s\"", + RelationGetRelationName(rel)), + errhint("Use the REFRESH MATERIALIZED VIEW command.")); + } else if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE) ereport(ERROR, (errcode(ERRCODE_WRONG_OBJECT_TYPE), diff --git a/src/test/regress/expected/copy.out b/src/test/regress/expected/copy.out index 06bae8c61ae..39af90f5292 100644 --- a/src/test/regress/expected/copy.out +++ b/src/test/regress/expected/copy.out @@ -338,3 +338,14 @@ create foreign table copytest_foreign_table (a int) server copytest_server; copy copytest_foreign_table from stdin (freeze); ERROR: cannot perform COPY FREEZE on a foreign table rollback; +-- COPY TO with materialized view +CREATE MATERIALIZED VIEW matview1 AS SELECT 1 as id; +CREATE MATERIALIZED VIEW matview2 AS SELECT 1 as id WITH NO DATA; +COPY matview1(id) TO stdout WITH (header); +id +1 +COPY matview2 TO stdout WITH (header); +ERROR: cannot copy from unpopulated materialized view "matview2" +HINT: Use the REFRESH MATERIALIZED VIEW command. +DROP MATERIALIZED VIEW matview1; +DROP MATERIALIZED VIEW matview2; diff --git a/src/test/regress/sql/copy.sql b/src/test/regress/sql/copy.sql index 3009bdfdf89..5df65924f8b 100644 --- a/src/test/regress/sql/copy.sql +++ b/src/test/regress/sql/copy.sql @@ -366,3 +366,11 @@ copy copytest_foreign_table from stdin (freeze); 1 \. rollback; + +-- COPY TO with materialized view +CREATE MATERIALIZED VIEW matview1 AS SELECT 1 as id; +CREATE MATERIALIZED VIEW matview2 AS SELECT 1 as id WITH NO DATA; +COPY matview1(id) TO stdout WITH (header); +COPY matview2 TO stdout WITH (header); +DROP MATERIALIZED VIEW matview1; +DROP MATERIALIZED VIEW matview2; -- 2.34.1