From e0dd23cd9bbfcae5af64ccc248564176826617d9 Mon Sep 17 00:00:00 2001 From: jian he Date: Fri, 26 Apr 2024 15:12:49 +0800 Subject: [PATCH v1 6/7] split sect1: "functions-info" from func.sgml "functions-info" lives in a new file: doc/src/sgml/func-info.sgml, it will hold doc/src/sgml/html/functions-info.html content. http://postgr.es/m/CACJufxEcMjjn-m6fpC2wXHsQbE5nyd%3Dxt6k-jDizBVUKK6O4KQ%40mail.gmail.com --- doc/src/sgml/filelist.sgml | 1 + doc/src/sgml/func-info.sgml | 3640 ++++++++++++++++++++++++++++++++++ doc/src/sgml/func.sgml | 3641 +---------------------------------- 3 files changed, 3642 insertions(+), 3640 deletions(-) create mode 100644 doc/src/sgml/func-info.sgml diff --git a/doc/src/sgml/filelist.sgml b/doc/src/sgml/filelist.sgml index 13694aca..4e80d2b4 100644 --- a/doc/src/sgml/filelist.sgml +++ b/doc/src/sgml/filelist.sgml @@ -23,6 +23,7 @@ + diff --git a/doc/src/sgml/func-info.sgml b/doc/src/sgml/func-info.sgml new file mode 100644 index 00000000..c77302ff --- /dev/null +++ b/doc/src/sgml/func-info.sgml @@ -0,0 +1,3640 @@ + + System Information Functions and Operators + + + The functions described in this section are used to obtain various + information about a PostgreSQL installation. + + + + Session Information Functions + + + shows several + functions that extract session and system information. + + + + In addition to the functions listed in this section, there are a number of + functions related to the statistics system that also provide system + information. See for more + information. + + + + Session Information Functions + + + + + Function + + + Description + + + + + + + + + current_catalog + + current_catalog + name + + + + current_database + + current_database () + name + + + Returns the name of the current database. (Databases are + called catalogs in the SQL standard, + so current_catalog is the standard's + spelling.) + + + + + + + current_query + + current_query () + text + + + Returns the text of the currently executing query, as submitted + by the client (which might contain more than one statement). + + + + + + + current_role + + current_role + name + + + This is equivalent to current_user. + + + + + + + current_schema + + + schema + current + + current_schema + name + + + current_schema () + name + + + Returns the name of the schema that is first in the search path (or a + null value if the search path is empty). This is the schema that will + be used for any tables or other named objects that are created without + specifying a target schema. + + + + + + + current_schemas + + + search path + current + + current_schemas ( include_implicit boolean ) + name[] + + + Returns an array of the names of all schemas presently in the + effective search path, in their priority order. (Items in the current + setting that do not correspond to + existing, searchable schemas are omitted.) If the Boolean argument + is true, then implicitly-searched system schemas + such as pg_catalog are included in the result. + + + + + + + current_user + + + user + current + + current_user + name + + + Returns the user name of the current execution context. + + + + + + + inet_client_addr + + inet_client_addr () + inet + + + Returns the IP address of the current client, + or NULL if the current connection is via a + Unix-domain socket. + + + + + + + inet_client_port + + inet_client_port () + integer + + + Returns the IP port number of the current client, + or NULL if the current connection is via a + Unix-domain socket. + + + + + + + inet_server_addr + + inet_server_addr () + inet + + + Returns the IP address on which the server accepted the current + connection, + or NULL if the current connection is via a + Unix-domain socket. + + + + + + + inet_server_port + + inet_server_port () + integer + + + Returns the IP port number on which the server accepted the current + connection, + or NULL if the current connection is via a + Unix-domain socket. + + + + + + + pg_backend_pid + + pg_backend_pid () + integer + + + Returns the process ID of the server process attached to the current + session. + + + + + + + pg_blocking_pids + + pg_blocking_pids ( integer ) + integer[] + + + Returns an array of the process ID(s) of the sessions that are + blocking the server process with the specified process ID from + acquiring a lock, or an empty array if there is no such server process + or it is not blocked. + + + One server process blocks another if it either holds a lock that + conflicts with the blocked process's lock request (hard block), or is + waiting for a lock that would conflict with the blocked process's lock + request and is ahead of it in the wait queue (soft block). When using + parallel queries the result always lists client-visible process IDs + (that is, pg_backend_pid results) even if the + actual lock is held or awaited by a child worker process. As a result + of that, there may be duplicated PIDs in the result. Also note that + when a prepared transaction holds a conflicting lock, it will be + represented by a zero process ID. + + + Frequent calls to this function could have some impact on database + performance, because it needs exclusive access to the lock manager's + shared state for a short time. + + + + + + + pg_conf_load_time + + pg_conf_load_time () + timestamp with time zone + + + Returns the time when the server configuration files were last loaded. + If the current session was alive at the time, this will be the time + when the session itself re-read the configuration files (so the + reading will vary a little in different sessions). Otherwise it is + the time when the postmaster process re-read the configuration files. + + + + + + + pg_current_logfile + + + Logging + pg_current_logfile function + + + current_logfiles + and the pg_current_logfile function + + + Logging + current_logfiles file and the pg_current_logfile + function + + pg_current_logfile ( text ) + text + + + Returns the path name of the log file currently in use by the logging + collector. The path includes the + directory and the individual log file name. The result + is NULL if the logging collector is disabled. + When multiple log files exist, each in a different + format, pg_current_logfile without an argument + returns the path of the file having the first format found in the + ordered list: stderr, + csvlog, jsonlog. + NULL is returned if no log file has any of these + formats. + To request information about a specific log file format, supply + either csvlog, jsonlog or + stderr as the + value of the optional parameter. The result is NULL + if the log format requested is not configured in + . + The result reflects the contents of + the current_logfiles file. + + + This function is restricted to superusers and roles with privileges of + the pg_monitor role by default, but other users can + be granted EXECUTE to run the function. + + + + + + + pg_my_temp_schema + + pg_my_temp_schema () + oid + + + Returns the OID of the current session's temporary schema, or zero if + it has none (because it has not created any temporary tables). + + + + + + + pg_is_other_temp_schema + + pg_is_other_temp_schema ( oid ) + boolean + + + Returns true if the given OID is the OID of another session's + temporary schema. (This can be useful, for example, to exclude other + sessions' temporary tables from a catalog display.) + + + + + + + pg_jit_available + + pg_jit_available () + boolean + + + Returns true if a JIT compiler extension is + available (see ) and the + configuration parameter is set to + on. + + + + + + + pg_listening_channels + + pg_listening_channels () + setof text + + + Returns the set of names of asynchronous notification channels that + the current session is listening to. + + + + + + + pg_notification_queue_usage + + pg_notification_queue_usage () + double precision + + + Returns the fraction (0–1) of the asynchronous notification + queue's maximum size that is currently occupied by notifications that + are waiting to be processed. + See and + for more information. + + + + + + + pg_postmaster_start_time + + pg_postmaster_start_time () + timestamp with time zone + + + Returns the time when the server started. + + + + + + + pg_safe_snapshot_blocking_pids + + pg_safe_snapshot_blocking_pids ( integer ) + integer[] + + + Returns an array of the process ID(s) of the sessions that are blocking + the server process with the specified process ID from acquiring a safe + snapshot, or an empty array if there is no such server process or it + is not blocked. + + + A session running a SERIALIZABLE transaction blocks + a SERIALIZABLE READ ONLY DEFERRABLE transaction + from acquiring a snapshot until the latter determines that it is safe + to avoid taking any predicate locks. See + for more information about + serializable and deferrable transactions. + + + Frequent calls to this function could have some impact on database + performance, because it needs access to the predicate lock manager's + shared state for a short time. + + + + + + + pg_trigger_depth + + pg_trigger_depth () + integer + + + Returns the current nesting level + of PostgreSQL triggers (0 if not called, + directly or indirectly, from inside a trigger). + + + + + + + session_user + + session_user + name + + + Returns the session user's name. + + + + + + + system_user + + system_user + text + + + Returns the authentication method and the identity (if any) that the + user presented during the authentication cycle before they were + assigned a database role. It is represented as + auth_method:identity or + NULL if the user has not been authenticated (for + example if Trust authentication has + been used). + + + + + + + user + + user + name + + + This is equivalent to current_user. + + + + +
+ + + + current_catalog, + current_role, + current_schema, + current_user, + session_user, + and user have special syntactic status + in SQL: they must be called without trailing + parentheses. In PostgreSQL, parentheses can optionally be used with + current_schema, but not with the others. + + + + + The session_user is normally the user who initiated + the current database connection; but superusers can change this setting + with . + The current_user is the user identifier + that is applicable for permission checking. Normally it is equal + to the session user, but it can be changed with + . + It also changes during the execution of + functions with the attribute SECURITY DEFINER. + In Unix parlance, the session user is the real user and + the current user is the effective user. + current_role and user are + synonyms for current_user. (The SQL standard draws + a distinction between current_role + and current_user, but PostgreSQL + does not, since it unifies users and roles into a single kind of entity.) + + + + + + Access Privilege Inquiry Functions + + + privilege + querying + + + + lists functions that + allow querying object access privileges programmatically. + (See for more information about + privileges.) + In these functions, the user whose privileges are being inquired about + can be specified by name or by OID + (pg_authid.oid), or if + the name is given as public then the privileges of the + PUBLIC pseudo-role are checked. Also, the user + argument can be omitted entirely, in which case + the current_user is assumed. + The object that is being inquired about can be specified either by name or + by OID, too. When specifying by name, a schema name can be included if + relevant. + The access privilege of interest is specified by a text string, which must + evaluate to one of the appropriate privilege keywords for the object's type + (e.g., SELECT). Optionally, WITH GRANT + OPTION can be added to a privilege type to test whether the + privilege is held with grant option. Also, multiple privilege types can be + listed separated by commas, in which case the result will be true if any of + the listed privileges is held. (Case of the privilege string is not + significant, and extra whitespace is allowed between but not within + privilege names.) + Some examples: + +SELECT has_table_privilege('myschema.mytable', 'select'); +SELECT has_table_privilege('joe', 'mytable', 'INSERT, SELECT WITH GRANT OPTION'); + + + + + Access Privilege Inquiry Functions + + + + + Function + + + Description + + + + + + + + + has_any_column_privilege + + has_any_column_privilege ( + user name or oid, + table text or oid, + privilege text ) + boolean + + + Does user have privilege for any column of table? + This succeeds either if the privilege is held for the whole table, or + if there is a column-level grant of the privilege for at least one + column. + Allowable privilege types are + SELECT, INSERT, + UPDATE, and REFERENCES. + + + + + + + has_column_privilege + + has_column_privilege ( + user name or oid, + table text or oid, + column text or smallint, + privilege text ) + boolean + + + Does user have privilege for the specified table column? + This succeeds either if the privilege is held for the whole table, or + if there is a column-level grant of the privilege for the column. + The column can be specified by name or by attribute number + (pg_attribute.attnum). + Allowable privilege types are + SELECT, INSERT, + UPDATE, and REFERENCES. + + + + + + + has_database_privilege + + has_database_privilege ( + user name or oid, + database text or oid, + privilege text ) + boolean + + + Does user have privilege for database? + Allowable privilege types are + CREATE, + CONNECT, + TEMPORARY, and + TEMP (which is equivalent to + TEMPORARY). + + + + + + + has_foreign_data_wrapper_privilege + + has_foreign_data_wrapper_privilege ( + user name or oid, + fdw text or oid, + privilege text ) + boolean + + + Does user have privilege for foreign-data wrapper? + The only allowable privilege type is USAGE. + + + + + + + has_function_privilege + + has_function_privilege ( + user name or oid, + function text or oid, + privilege text ) + boolean + + + Does user have privilege for function? + The only allowable privilege type is EXECUTE. + + + When specifying a function by name rather than by OID, the allowed + input is the same as for the regprocedure data type (see + ). + An example is: + +SELECT has_function_privilege('joeuser', 'myfunc(int, text)', 'execute'); + + + + + + + + has_language_privilege + + has_language_privilege ( + user name or oid, + language text or oid, + privilege text ) + boolean + + + Does user have privilege for language? + The only allowable privilege type is USAGE. + + + + + + + has_parameter_privilege + + has_parameter_privilege ( + user name or oid, + parameter text, + privilege text ) + boolean + + + Does user have privilege for configuration parameter? + The parameter name is case-insensitive. + Allowable privilege types are SET + and ALTER SYSTEM. + + + + + + + has_schema_privilege + + has_schema_privilege ( + user name or oid, + schema text or oid, + privilege text ) + boolean + + + Does user have privilege for schema? + Allowable privilege types are + CREATE and + USAGE. + + + + + + + has_sequence_privilege + + has_sequence_privilege ( + user name or oid, + sequence text or oid, + privilege text ) + boolean + + + Does user have privilege for sequence? + Allowable privilege types are + USAGE, + SELECT, and + UPDATE. + + + + + + + has_server_privilege + + has_server_privilege ( + user name or oid, + server text or oid, + privilege text ) + boolean + + + Does user have privilege for foreign server? + The only allowable privilege type is USAGE. + + + + + + + has_table_privilege + + has_table_privilege ( + user name or oid, + table text or oid, + privilege text ) + boolean + + + Does user have privilege for table? + Allowable privilege types + are SELECT, INSERT, + UPDATE, DELETE, + TRUNCATE, REFERENCES, + TRIGGER, and MAINTAIN. + + + + + + + has_tablespace_privilege + + has_tablespace_privilege ( + user name or oid, + tablespace text or oid, + privilege text ) + boolean + + + Does user have privilege for tablespace? + The only allowable privilege type is CREATE. + + + + + + + has_type_privilege + + has_type_privilege ( + user name or oid, + type text or oid, + privilege text ) + boolean + + + Does user have privilege for data type? + The only allowable privilege type is USAGE. + When specifying a type by name rather than by OID, the allowed input + is the same as for the regtype data type (see + ). + + + + + + + pg_has_role + + pg_has_role ( + user name or oid, + role text or oid, + privilege text ) + boolean + + + Does user have privilege for role? + Allowable privilege types are + MEMBER, USAGE, + and SET. + MEMBER denotes direct or indirect membership in + the role without regard to what specific privileges may be conferred. + USAGE denotes whether the privileges of the role + are immediately available without doing SET ROLE, + while SET denotes whether it is possible to change + to the role using the SET ROLE command. + This function does not allow the special case of + setting user to public, + because the PUBLIC pseudo-role can never be a member of real roles. + + + + + + + row_security_active + + row_security_active ( + table text or oid ) + boolean + + + Is row-level security active for the specified table in the context of + the current user and current environment? + + + + +
+ + + shows the operators + available for the aclitem type, which is the catalog + representation of access privileges. See + for information about how to read access privilege values. + + + + <type>aclitem</type> Operators + + + + + Operator + + + Description + + + Example(s) + + + + + + + + + aclitemeq + + aclitem = aclitem + boolean + + + Are aclitems equal? (Notice that + type aclitem lacks the usual set of comparison + operators; it has only equality. In turn, aclitem + arrays can only be compared for equality.) + + + 'calvin=r*w/hobbes'::aclitem = 'calvin=r*w*/hobbes'::aclitem + f + + + + + + + aclcontains + + aclitem[] @> aclitem + boolean + + + Does array contain the specified privileges? (This is true if there + is an array entry that matches the aclitem's grantee and + grantor, and has at least the specified set of privileges.) + + + '{calvin=r*w/hobbes,hobbes=r*w*/postgres}'::aclitem[] @> 'calvin=r*/hobbes'::aclitem + t + + + + + + aclitem[] ~ aclitem + boolean + + + This is a deprecated alias for @>. + + + '{calvin=r*w/hobbes,hobbes=r*w*/postgres}'::aclitem[] ~ 'calvin=r*/hobbes'::aclitem + t + + + + +
+ + + shows some additional + functions to manage the aclitem type. + + + + <type>aclitem</type> Functions + + + + + Function + + + Description + + + + + + + + + acldefault + + acldefault ( + type "char", + ownerId oid ) + aclitem[] + + + Constructs an aclitem array holding the default access + privileges for an object of type type belonging + to the role with OID ownerId. This represents + the access privileges that will be assumed when an object's ACL entry + is null. (The default access privileges are described in + .) + The type parameter must be one of + 'c' for COLUMN, + 'r' for TABLE and table-like objects, + 's' for SEQUENCE, + 'd' for DATABASE, + 'f' for FUNCTION or PROCEDURE, + 'l' for LANGUAGE, + 'L' for LARGE OBJECT, + 'n' for SCHEMA, + 'p' for PARAMETER, + 't' for TABLESPACE, + 'F' for FOREIGN DATA WRAPPER, + 'S' for FOREIGN SERVER, + or + 'T' for TYPE or DOMAIN. + + + + + + + aclexplode + + aclexplode ( aclitem[] ) + setof record + ( grantor oid, + grantee oid, + privilege_type text, + is_grantable boolean ) + + + Returns the aclitem array as a set of rows. + If the grantee is the pseudo-role PUBLIC, it is represented by zero in + the grantee column. Each granted privilege is + represented as SELECT, INSERT, + etc (see for a full list). + Note that each privilege is broken out as a separate row, so + only one keyword appears in the privilege_type + column. + + + + + + + makeaclitem + + makeaclitem ( + grantee oid, + grantor oid, + privileges text, + is_grantable boolean ) + aclitem + + + Constructs an aclitem with the given properties. + privileges is a comma-separated list of + privilege names such as SELECT, + INSERT, etc, all of which are set in the + result. (Case of the privilege string is not significant, and + extra whitespace is allowed between but not within privilege + names.) + + + + +
+ + + + + Schema Visibility Inquiry Functions + + + shows functions that + determine whether a certain object is visible in the + current schema search path. + For example, a table is said to be visible if its + containing schema is in the search path and no table of the same + name appears earlier in the search path. This is equivalent to the + statement that the table can be referenced by name without explicit + schema qualification. Thus, to list the names of all visible tables: + +SELECT relname FROM pg_class WHERE pg_table_is_visible(oid); + + For functions and operators, an object in the search path is said to be + visible if there is no object of the same name and argument data + type(s) earlier in the path. For operator classes and families, + both the name and the associated index access method are considered. + + + + search path + object visibility + + + + Schema Visibility Inquiry Functions + + + + + Function + + + Description + + + + + + + + + pg_collation_is_visible + + pg_collation_is_visible ( collation oid ) + boolean + + + Is collation visible in search path? + + + + + + + pg_conversion_is_visible + + pg_conversion_is_visible ( conversion oid ) + boolean + + + Is conversion visible in search path? + + + + + + + pg_function_is_visible + + pg_function_is_visible ( function oid ) + boolean + + + Is function visible in search path? + (This also works for procedures and aggregates.) + + + + + + + pg_opclass_is_visible + + pg_opclass_is_visible ( opclass oid ) + boolean + + + Is operator class visible in search path? + + + + + + + pg_operator_is_visible + + pg_operator_is_visible ( operator oid ) + boolean + + + Is operator visible in search path? + + + + + + + pg_opfamily_is_visible + + pg_opfamily_is_visible ( opclass oid ) + boolean + + + Is operator family visible in search path? + + + + + + + pg_statistics_obj_is_visible + + pg_statistics_obj_is_visible ( stat oid ) + boolean + + + Is statistics object visible in search path? + + + + + + + pg_table_is_visible + + pg_table_is_visible ( table oid ) + boolean + + + Is table visible in search path? + (This works for all types of relations, including views, materialized + views, indexes, sequences and foreign tables.) + + + + + + + pg_ts_config_is_visible + + pg_ts_config_is_visible ( config oid ) + boolean + + + Is text search configuration visible in search path? + + + + + + + pg_ts_dict_is_visible + + pg_ts_dict_is_visible ( dict oid ) + boolean + + + Is text search dictionary visible in search path? + + + + + + + pg_ts_parser_is_visible + + pg_ts_parser_is_visible ( parser oid ) + boolean + + + Is text search parser visible in search path? + + + + + + + pg_ts_template_is_visible + + pg_ts_template_is_visible ( template oid ) + boolean + + + Is text search template visible in search path? + + + + + + + pg_type_is_visible + + pg_type_is_visible ( type oid ) + boolean + + + Is type (or domain) visible in search path? + + + + +
+ + + All these functions require object OIDs to identify the object to be + checked. If you want to test an object by name, it is convenient to use + the OID alias types (regclass, regtype, + regprocedure, regoperator, regconfig, + or regdictionary), + for example: + +SELECT pg_type_is_visible('myschema.widget'::regtype); + + Note that it would not make much sense to test a non-schema-qualified + type name in this way — if the name can be recognized at all, it must be visible. + + + + + + System Catalog Information Functions + + + lists functions that + extract information from the system catalogs. + + + + System Catalog Information Functions + + + + + Function + + + Description + + + + + + + + + format_type + + format_type ( type oid, typemod integer ) + text + + + Returns the SQL name for a data type that is identified by its type + OID and possibly a type modifier. Pass NULL for the type modifier if + no specific modifier is known. + + + + + + + pg_basetype + + pg_basetype ( regtype ) + regtype + + + Returns the OID of the base type of a domain identified by its + type OID. If the argument is the OID of a non-domain type, + returns the argument as-is. Returns NULL if the argument is + not a valid type OID. If there's a chain of domain dependencies, + it will recurse until finding the base type. + + + Assuming CREATE DOMAIN mytext AS text: + + + pg_basetype('mytext'::regtype) + text + + + + + + + pg_char_to_encoding + + pg_char_to_encoding ( encoding name ) + integer + + + Converts the supplied encoding name into an integer representing the + internal identifier used in some system catalog tables. + Returns -1 if an unknown encoding name is provided. + + + + + + + pg_encoding_to_char + + pg_encoding_to_char ( encoding integer ) + name + + + Converts the integer used as the internal identifier of an encoding in some + system catalog tables into a human-readable string. + Returns an empty string if an invalid encoding number is provided. + + + + + + + pg_get_catalog_foreign_keys + + pg_get_catalog_foreign_keys () + setof record + ( fktable regclass, + fkcols text[], + pktable regclass, + pkcols text[], + is_array boolean, + is_opt boolean ) + + + Returns a set of records describing the foreign key relationships + that exist within the PostgreSQL system + catalogs. + The fktable column contains the name of the + referencing catalog, and the fkcols column + contains the name(s) of the referencing column(s). Similarly, + the pktable column contains the name of the + referenced catalog, and the pkcols column + contains the name(s) of the referenced column(s). + If is_array is true, the last referencing + column is an array, each of whose elements should match some entry + in the referenced catalog. + If is_opt is true, the referencing column(s) + are allowed to contain zeroes instead of a valid reference. + + + + + + + pg_get_constraintdef + + pg_get_constraintdef ( constraint oid , pretty boolean ) + text + + + Reconstructs the creating command for a constraint. + (This is a decompiled reconstruction, not the original text + of the command.) + + + + + + + pg_get_expr + + pg_get_expr ( expr pg_node_tree, relation oid , pretty boolean ) + text + + + Decompiles the internal form of an expression stored in the system + catalogs, such as the default value for a column. If the expression + might contain Vars, specify the OID of the relation they refer to as + the second parameter; if no Vars are expected, passing zero is + sufficient. + + + + + + + pg_get_functiondef + + pg_get_functiondef ( func oid ) + text + + + Reconstructs the creating command for a function or procedure. + (This is a decompiled reconstruction, not the original text + of the command.) + The result is a complete CREATE OR REPLACE FUNCTION + or CREATE OR REPLACE PROCEDURE statement. + + + + + + + pg_get_function_arguments + + pg_get_function_arguments ( func oid ) + text + + + Reconstructs the argument list of a function or procedure, in the form + it would need to appear in within CREATE FUNCTION + (including default values). + + + + + + + pg_get_function_identity_arguments + + pg_get_function_identity_arguments ( func oid ) + text + + + Reconstructs the argument list necessary to identify a function or + procedure, in the form it would need to appear in within commands such + as ALTER FUNCTION. This form omits default values. + + + + + + + pg_get_function_result + + pg_get_function_result ( func oid ) + text + + + Reconstructs the RETURNS clause of a function, in + the form it would need to appear in within CREATE + FUNCTION. Returns NULL for a procedure. + + + + + + + pg_get_indexdef + + pg_get_indexdef ( index oid , column integer, pretty boolean ) + text + + + Reconstructs the creating command for an index. + (This is a decompiled reconstruction, not the original text + of the command.) If column is supplied and is + not zero, only the definition of that column is reconstructed. + + + + + + + pg_get_keywords + + pg_get_keywords () + setof record + ( word text, + catcode "char", + barelabel boolean, + catdesc text, + baredesc text ) + + + Returns a set of records describing the SQL keywords recognized by the + server. The word column contains the + keyword. The catcode column contains a + category code: U for an unreserved + keyword, C for a keyword that can be a column + name, T for a keyword that can be a type or + function name, or R for a fully reserved keyword. + The barelabel column + contains true if the keyword can be used as + a bare column label in SELECT lists, + or false if it can only be used + after AS. + The catdesc column contains a + possibly-localized string describing the keyword's category. + The baredesc column contains a + possibly-localized string describing the keyword's column label status. + + + + + + + pg_get_partkeydef + + pg_get_partkeydef ( table oid ) + text + + + Reconstructs the definition of a partitioned table's partition + key, in the form it would have in the PARTITION + BY clause of CREATE TABLE. + (This is a decompiled reconstruction, not the original text + of the command.) + + + + + + + pg_get_ruledef + + pg_get_ruledef ( rule oid , pretty boolean ) + text + + + Reconstructs the creating command for a rule. + (This is a decompiled reconstruction, not the original text + of the command.) + + + + + + + pg_get_serial_sequence + + pg_get_serial_sequence ( table text, column text ) + text + + + Returns the name of the sequence associated with a column, + or NULL if no sequence is associated with the column. + If the column is an identity column, the associated sequence is the + sequence internally created for that column. + For columns created using one of the serial types + (serial, smallserial, bigserial), + it is the sequence created for that serial column definition. + In the latter case, the association can be modified or removed + with ALTER SEQUENCE OWNED BY. + (This function probably should have been + called pg_get_owned_sequence; its current name + reflects the fact that it has historically been used with serial-type + columns.) The first parameter is a table name with optional + schema, and the second parameter is a column name. Because the first + parameter potentially contains both schema and table names, it is + parsed per usual SQL rules, meaning it is lower-cased by default. + The second parameter, being just a column name, is treated literally + and so has its case preserved. The result is suitably formatted + for passing to the sequence functions (see + ). + + + A typical use is in reading the current value of the sequence for an + identity or serial column, for example: + +SELECT currval(pg_get_serial_sequence('sometable', 'id')); + + + + + + + + pg_get_statisticsobjdef + + pg_get_statisticsobjdef ( statobj oid ) + text + + + Reconstructs the creating command for an extended statistics object. + (This is a decompiled reconstruction, not the original text + of the command.) + + + + + + + pg_get_triggerdef + +pg_get_triggerdef ( trigger oid , pretty boolean ) + text + + + Reconstructs the creating command for a trigger. + (This is a decompiled reconstruction, not the original text + of the command.) + + + + + + + pg_get_userbyid + + pg_get_userbyid ( role oid ) + name + + + Returns a role's name given its OID. + + + + + + + pg_get_viewdef + + pg_get_viewdef ( view oid , pretty boolean ) + text + + + Reconstructs the underlying SELECT command for a + view or materialized view. (This is a decompiled reconstruction, not + the original text of the command.) + + + + + + pg_get_viewdef ( view oid, wrap_column integer ) + text + + + Reconstructs the underlying SELECT command for a + view or materialized view. (This is a decompiled reconstruction, not + the original text of the command.) In this form of the function, + pretty-printing is always enabled, and long lines are wrapped to try + to keep them shorter than the specified number of columns. + + + + + + pg_get_viewdef ( view text , pretty boolean ) + text + + + Reconstructs the underlying SELECT command for a + view or materialized view, working from a textual name for the view + rather than its OID. (This is deprecated; use the OID variant + instead.) + + + + + + + pg_index_column_has_property + + pg_index_column_has_property ( index regclass, column integer, property text ) + boolean + + + Tests whether an index column has the named property. + Common index column properties are listed in + . + (Note that extension access methods can define additional property + names for their indexes.) + NULL is returned if the property name is not known + or does not apply to the particular object, or if the OID or column + number does not identify a valid object. + + + + + + + pg_index_has_property + + pg_index_has_property ( index regclass, property text ) + boolean + + + Tests whether an index has the named property. + Common index properties are listed in + . + (Note that extension access methods can define additional property + names for their indexes.) + NULL is returned if the property name is not known + or does not apply to the particular object, or if the OID does not + identify a valid object. + + + + + + + pg_indexam_has_property + + pg_indexam_has_property ( am oid, property text ) + boolean + + + Tests whether an index access method has the named property. + Access method properties are listed in + . + NULL is returned if the property name is not known + or does not apply to the particular object, or if the OID does not + identify a valid object. + + + + + + + pg_options_to_table + + pg_options_to_table ( options_array text[] ) + setof record + ( option_name text, + option_value text ) + + + Returns the set of storage options represented by a value from + pg_class.reloptions or + pg_attribute.attoptions. + + + + + + + pg_settings_get_flags + + pg_settings_get_flags ( guc text ) + text[] + + + Returns an array of the flags associated with the given GUC, or + NULL if it does not exist. The result is + an empty array if the GUC exists but there are no flags to show. + Only the most useful flags listed in + are exposed. + + + + + + + pg_tablespace_databases + + pg_tablespace_databases ( tablespace oid ) + setof oid + + + Returns the set of OIDs of databases that have objects stored in the + specified tablespace. If this function returns any rows, the + tablespace is not empty and cannot be dropped. To identify the specific + objects populating the tablespace, you will need to connect to the + database(s) identified by pg_tablespace_databases + and query their pg_class catalogs. + + + + + + + pg_tablespace_location + + pg_tablespace_location ( tablespace oid ) + text + + + Returns the file system path that this tablespace is located in. + + + + + + + pg_typeof + + pg_typeof ( "any" ) + regtype + + + Returns the OID of the data type of the value that is passed to it. + This can be helpful for troubleshooting or dynamically constructing + SQL queries. The function is declared as + returning regtype, which is an OID alias type (see + ); this means that it is the same as an + OID for comparison purposes but displays as a type name. + + + pg_typeof(33) + integer + + + + + + + COLLATION FOR + + COLLATION FOR ( "any" ) + text + + + Returns the name of the collation of the value that is passed to it. + The value is quoted and schema-qualified if necessary. If no + collation was derived for the argument expression, + then NULL is returned. If the argument is not of a + collatable data type, then an error is raised. + + + collation for ('foo'::text) + "default" + + + collation for ('foo' COLLATE "de_DE") + "de_DE" + + + + + + + to_regclass + + to_regclass ( text ) + regclass + + + Translates a textual relation name to its OID. A similar result is + obtained by casting the string to type regclass (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found. + + + + + + + to_regcollation + + to_regcollation ( text ) + regcollation + + + Translates a textual collation name to its OID. A similar result is + obtained by casting the string to type regcollation (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found. + + + + + + + to_regnamespace + + to_regnamespace ( text ) + regnamespace + + + Translates a textual schema name to its OID. A similar result is + obtained by casting the string to type regnamespace (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found. + + + + + + + to_regoper + + to_regoper ( text ) + regoper + + + Translates a textual operator name to its OID. A similar result is + obtained by casting the string to type regoper (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found or is ambiguous. + + + + + + + to_regoperator + + to_regoperator ( text ) + regoperator + + + Translates a textual operator name (with parameter types) to its OID. A similar result is + obtained by casting the string to type regoperator (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found. + + + + + + + to_regproc + + to_regproc ( text ) + regproc + + + Translates a textual function or procedure name to its OID. A similar result is + obtained by casting the string to type regproc (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found or is ambiguous. + + + + + + + to_regprocedure + + to_regprocedure ( text ) + regprocedure + + + Translates a textual function or procedure name (with argument types) to its OID. A similar result is + obtained by casting the string to type regprocedure (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found. + + + + + + + to_regrole + + to_regrole ( text ) + regrole + + + Translates a textual role name to its OID. A similar result is + obtained by casting the string to type regrole (see + ); however, this function will return + NULL rather than throwing an error if the name is + not found. + + + + + + + to_regtype + + to_regtype ( text ) + regtype + + + Parses a string of text, extracts a potential type name from it, + and translates that name into a type OID. A syntax error in the + string will result in an error; but if the string is a + syntactically valid type name that happens not to be found in the + catalogs, the result is NULL. A similar result + is obtained by casting the string to type regtype + (see ), except that that will throw + error for name not found. + + + + + + + to_regtypemod + + to_regtypemod ( text ) + integer + + + Parses a string of text, extracts a potential type name from it, + and translates its type modifier, if any. A syntax error in the + string will result in an error; but if the string is a + syntactically valid type name that happens not to be found in the + catalogs, the result is NULL. The result is + -1 if no type modifier is present. + + + to_regtypemod can be combined with + to produce appropriate inputs for + , allowing a string representing a + type name to be canonicalized. + + + format_type(to_regtype('varchar(32)'), to_regtypemod('varchar(32)')) + character varying(32) + + + + +
+ + + Most of the functions that reconstruct (decompile) database objects + have an optional pretty flag, which + if true causes the result to + be pretty-printed. Pretty-printing suppresses unnecessary + parentheses and adds whitespace for legibility. + The pretty-printed format is more readable, but the default format + is more likely to be interpreted the same way by future versions of + PostgreSQL; so avoid using pretty-printed output + for dump purposes. Passing false for + the pretty parameter yields the same result as + omitting the parameter. + + + + Index Column Properties + + + NameDescription + + + + asc + Does the column sort in ascending order on a forward scan? + + + + desc + Does the column sort in descending order on a forward scan? + + + + nulls_first + Does the column sort with nulls first on a forward scan? + + + + nulls_last + Does the column sort with nulls last on a forward scan? + + + + orderable + Does the column possess any defined sort ordering? + + + + distance_orderable + Can the column be scanned in order by a distance + operator, for example ORDER BY col <-> constant ? + + + + returnable + Can the column value be returned by an index-only scan? + + + + search_array + Does the column natively support col = ANY(array) + searches? + + + + search_nulls + Does the column support IS NULL and + IS NOT NULL searches? + + + + +
+ + + Index Properties + + + NameDescription + + + + clusterable + Can the index be used in a CLUSTER command? + + + + index_scan + Does the index support plain (non-bitmap) scans? + + + + bitmap_scan + Does the index support bitmap scans? + + + + backward_scan + Can the scan direction be changed in mid-scan (to + support FETCH BACKWARD on a cursor without + needing materialization)? + + + + +
+ + + Index Access Method Properties + + + NameDescription + + + + can_order + Does the access method support ASC, + DESC and related keywords in + CREATE INDEX? + + + + can_unique + Does the access method support unique indexes? + + + + can_multi_col + Does the access method support indexes with multiple columns? + + + + can_exclude + Does the access method support exclusion constraints? + + + + can_include + Does the access method support the INCLUDE + clause of CREATE INDEX? + + + + +
+ + + GUC Flags + + + FlagDescription + + + + EXPLAIN + Parameters with this flag are included in + EXPLAIN (SETTINGS) commands. + + + + NO_SHOW_ALL + Parameters with this flag are excluded from + SHOW ALL commands. + + + + NO_RESET + Parameters with this flag do not support + RESET commands. + + + + NO_RESET_ALL + Parameters with this flag are excluded from + RESET ALL commands. + + + + NOT_IN_SAMPLE + Parameters with this flag are not included in + postgresql.conf by default. + + + + RUNTIME_COMPUTED + Parameters with this flag are runtime-computed ones. + + + + +
+ + + + + Object Information and Addressing Functions + + + lists functions related to + database object identification and addressing. + + + + Object Information and Addressing Functions + + + + + Function + + + Description + + + + + + + + + pg_describe_object + + pg_describe_object ( classid oid, objid oid, objsubid integer ) + text + + + Returns a textual description of a database object identified by + catalog OID, object OID, and sub-object ID (such as a column number + within a table; the sub-object ID is zero when referring to a whole + object). This description is intended to be human-readable, and might + be translated, depending on server configuration. This is especially + useful to determine the identity of an object referenced in the + pg_depend catalog. This function returns + NULL values for undefined objects. + + + + + + + pg_identify_object + + pg_identify_object ( classid oid, objid oid, objsubid integer ) + record + ( type text, + schema text, + name text, + identity text ) + + + Returns a row containing enough information to uniquely identify the + database object specified by catalog OID, object OID and sub-object + ID. + This information is intended to be machine-readable, and is never + translated. + type identifies the type of database object; + schema is the schema name that the object + belongs in, or NULL for object types that do not + belong to schemas; + name is the name of the object, quoted if + necessary, if the name (along with schema name, if pertinent) is + sufficient to uniquely identify the object, + otherwise NULL; + identity is the complete object identity, with + the precise format depending on object type, and each name within the + format being schema-qualified and quoted as necessary. Undefined + objects are identified with NULL values. + + + + + + + pg_identify_object_as_address + + pg_identify_object_as_address ( classid oid, objid oid, objsubid integer ) + record + ( type text, + object_names text[], + object_args text[] ) + + + Returns a row containing enough information to uniquely identify the + database object specified by catalog OID, object OID and sub-object + ID. + The returned information is independent of the current server, that + is, it could be used to identify an identically named object in + another server. + type identifies the type of database object; + object_names and + object_args + are text arrays that together form a reference to the object. + These three values can be passed + to pg_get_object_address to obtain the internal + address of the object. + + + + + + + pg_get_object_address + + pg_get_object_address ( type text, object_names text[], object_args text[] ) + record + ( classid oid, + objid oid, + objsubid integer ) + + + Returns a row containing enough information to uniquely identify the + database object specified by a type code and object name and argument + arrays. + The returned values are the ones that would be used in system catalogs + such as pg_depend; they can be passed to + other system functions such as pg_describe_object + or pg_identify_object. + classid is the OID of the system catalog + containing the object; + objid is the OID of the object itself, and + objsubid is the sub-object ID, or zero if none. + This function is the inverse + of pg_identify_object_as_address. + Undefined objects are identified with NULL values. + + + + +
+ + + + + Comment Information Functions + + + comment + about database objects + + + + The functions shown in + extract comments previously stored with the + command. A null value is returned if no + comment could be found for the specified parameters. + + + + Comment Information Functions + + + + + Function + + + Description + + + + + + + + + col_description + + col_description ( table oid, column integer ) + text + + + Returns the comment for a table column, which is specified by the OID + of its table and its column number. + (obj_description cannot be used for table + columns, since columns do not have OIDs of their own.) + + + + + + + obj_description + + obj_description ( object oid, catalog name ) + text + + + Returns the comment for a database object specified by its OID and the + name of the containing system catalog. For + example, obj_description(123456, 'pg_class') would + retrieve the comment for the table with OID 123456. + + + + + + obj_description ( object oid ) + text + + + Returns the comment for a database object specified by its OID alone. + This is deprecated since there is no guarantee + that OIDs are unique across different system catalogs; therefore, the + wrong comment might be returned. + + + + + + + shobj_description + + shobj_description ( object oid, catalog name ) + text + + + Returns the comment for a shared database object specified by its OID + and the name of the containing system catalog. This is just + like obj_description except that it is used for + retrieving comments on shared objects (that is, databases, roles, and + tablespaces). Some system catalogs are global to all databases within + each cluster, and the descriptions for objects in them are stored + globally as well. + + + + +
+ + + + + Data Validity Checking Functions + + + The functions shown in + can be helpful for checking validity of proposed input data. + + + + Data Validity Checking Functions + + + + + Function + + + Description + + + Example(s) + + + + + + + + + pg_input_is_valid + + pg_input_is_valid ( + string text, + type text + ) + boolean + + + Tests whether the given string is valid + input for the specified data type, returning true or false. + + + This function will only work as desired if the data type's input + function has been updated to report invalid input as + a soft error. Otherwise, invalid input will abort + the transaction, just as if the string had been cast to the type + directly. + + + pg_input_is_valid('42', 'integer') + t + + + pg_input_is_valid('42000000000', 'integer') + f + + + pg_input_is_valid('1234.567', 'numeric(7,4)') + f + + + + + + pg_input_error_info + + pg_input_error_info ( + string text, + type text + ) + record + ( message text, + detail text, + hint text, + sql_error_code text ) + + + Tests whether the given string is valid + input for the specified data type; if not, return the details of + the error that would have been thrown. If the input is valid, the + results are NULL. The inputs are the same as + for pg_input_is_valid. + + + This function will only work as desired if the data type's input + function has been updated to report invalid input as + a soft error. Otherwise, invalid input will abort + the transaction, just as if the string had been cast to the type + directly. + + + select * from pg_input_error_info('42000000000', 'integer') + + + message | detail | hint | sql_error_code +------------------------------------------------------+--------+------+---------------- + value "42000000000" is out of range for type integer | | | 22003 + + + + select message, detail from pg_input_error_info('1234.567', 'numeric(7,4)') + + + message | detail +------------------------+----------------------------------&zwsp;------------------------------------------------- + numeric field overflow | A field with precision 7, scale 4 must round to an absolute value less than 10^3. + + + + + +
+ + + + + Transaction ID and Snapshot Information Functions + + + The functions shown in + provide server transaction information in an exportable form. The main + use of these functions is to determine which transactions were committed + between two snapshots. + + + + Transaction ID and Snapshot Information Functions + + + + + Function + + + Description + + + + + + + + + pg_current_xact_id + + pg_current_xact_id () + xid8 + + + Returns the current transaction's ID. It will assign a new one if the + current transaction does not have one already (because it has not + performed any database updates); see for details. If executed in a + subtransaction, this will return the top-level transaction ID; + see for details. + + + + + + + pg_current_xact_id_if_assigned + + pg_current_xact_id_if_assigned () + xid8 + + + Returns the current transaction's ID, or NULL if no + ID is assigned yet. (It's best to use this variant if the transaction + might otherwise be read-only, to avoid unnecessary consumption of an + XID.) + If executed in a subtransaction, this will return the top-level + transaction ID. + + + + + + + pg_xact_status + + pg_xact_status ( xid8 ) + text + + + Reports the commit status of a recent transaction. + The result is one of in progress, + committed, or aborted, + provided that the transaction is recent enough that the system retains + the commit status of that transaction. + If it is old enough that no references to the transaction survive in + the system and the commit status information has been discarded, the + result is NULL. + Applications might use this function, for example, to determine + whether their transaction committed or aborted after the application + and database server become disconnected while + a COMMIT is in progress. + Note that prepared transactions are reported as in + progress; applications must check pg_prepared_xacts + if they need to determine whether a transaction ID belongs to a + prepared transaction. + + + + + + + pg_current_snapshot + + pg_current_snapshot () + pg_snapshot + + + Returns a current snapshot, a data structure + showing which transaction IDs are now in-progress. + Only top-level transaction IDs are included in the snapshot; + subtransaction IDs are not shown; see + for details. + + + + + + + pg_snapshot_xip + + pg_snapshot_xip ( pg_snapshot ) + setof xid8 + + + Returns the set of in-progress transaction IDs contained in a snapshot. + + + + + + + pg_snapshot_xmax + + pg_snapshot_xmax ( pg_snapshot ) + xid8 + + + Returns the xmax of a snapshot. + + + + + + + pg_snapshot_xmin + + pg_snapshot_xmin ( pg_snapshot ) + xid8 + + + Returns the xmin of a snapshot. + + + + + + + pg_visible_in_snapshot + + pg_visible_in_snapshot ( xid8, pg_snapshot ) + boolean + + + Is the given transaction ID visible according + to this snapshot (that is, was it completed before the snapshot was + taken)? Note that this function will not give the correct answer for + a subtransaction ID (subxid); see for + details. + + + + +
+ + + The internal transaction ID type xid is 32 bits wide and + wraps around every 4 billion transactions. However, + the functions shown in use a + 64-bit type xid8 that does not wrap around during the life + of an installation and can be converted to xid by casting if + required; see for details. + The data type pg_snapshot stores information about + transaction ID visibility at a particular moment in time. Its components + are described in . + pg_snapshot's textual representation is + xmin:xmax:xip_list. + For example 10:20:10,14,15 means + xmin=10, xmax=20, xip_list=10, 14, 15. + + + + Snapshot Components + + + + Name + Description + + + + + + xmin + + Lowest transaction ID that was still active. All transaction IDs + less than xmin are either committed and visible, + or rolled back and dead. + + + + + xmax + + One past the highest completed transaction ID. All transaction IDs + greater than or equal to xmax had not yet + completed as of the time of the snapshot, and thus are invisible. + + + + + xip_list + + Transactions in progress at the time of the snapshot. A transaction + ID that is xmin <= X < + xmax and not in this list was already completed at the time + of the snapshot, and thus is either visible or dead according to its + commit status. This list does not include the transaction IDs of + subtransactions (subxids). + + + + +
+ + + In releases of PostgreSQL before 13 there was + no xid8 type, so variants of these functions were provided + that used bigint to represent a 64-bit XID, with a + correspondingly distinct snapshot data type txid_snapshot. + These older functions have txid in their names. They + are still supported for backward compatibility, but may be removed from a + future release. See . + + + + Deprecated Transaction ID and Snapshot Information Functions + + + + + Function + + + Description + + + + + + + + + age + + age ( xid ) + integer + + + Returns the number of transactions between the supplied + transaction id and the current transaction counter. + + + + + + + mxid_age + + mxid_age ( xid ) + integer + + + Returns the number of multixacts IDs between the supplied + multixact ID and the current multixacts counter. + + + + + + + txid_current + + txid_current () + bigint + + + See pg_current_xact_id(). + + + + + + + txid_current_if_assigned + + txid_current_if_assigned () + bigint + + + See pg_current_xact_id_if_assigned(). + + + + + + + txid_current_snapshot + + txid_current_snapshot () + txid_snapshot + + + See pg_current_snapshot(). + + + + + + + txid_snapshot_xip + + txid_snapshot_xip ( txid_snapshot ) + setof bigint + + + See pg_snapshot_xip(). + + + + + + + txid_snapshot_xmax + + txid_snapshot_xmax ( txid_snapshot ) + bigint + + + See pg_snapshot_xmax(). + + + + + + + txid_snapshot_xmin + + txid_snapshot_xmin ( txid_snapshot ) + bigint + + + See pg_snapshot_xmin(). + + + + + + + txid_visible_in_snapshot + + txid_visible_in_snapshot ( bigint, txid_snapshot ) + boolean + + + See pg_visible_in_snapshot(). + + + + + + + txid_status + + txid_status ( bigint ) + text + + + See pg_xact_status(). + + + + +
+ + + + + Committed Transaction Information Functions + + + The functions shown in + provide information about when past transactions were committed. + They only provide useful data when the + configuration option is + enabled, and only for transactions that were committed after it was + enabled. Commit timestamp information is routinely removed during + vacuum. + + + + Committed Transaction Information Functions + + + + + Function + + + Description + + + + + + + + + pg_xact_commit_timestamp + + pg_xact_commit_timestamp ( xid ) + timestamp with time zone + + + Returns the commit timestamp of a transaction. + + + + + + + pg_xact_commit_timestamp_origin + + pg_xact_commit_timestamp_origin ( xid ) + record + ( timestamp timestamp with time zone, + roident oid) + + + Returns the commit timestamp and replication origin of a transaction. + + + + + + + pg_last_committed_xact + + pg_last_committed_xact () + record + ( xid xid, + timestamp timestamp with time zone, + roident oid ) + + + Returns the transaction ID, commit timestamp and replication origin + of the latest committed transaction. + + + + +
+ + + + + Control Data Functions + + + The functions shown in + print information initialized during initdb, such + as the catalog version. They also show information about write-ahead + logging and checkpoint processing. This information is cluster-wide, + not specific to any one database. These functions provide most of the same + information, from the same source, as the + application. + + + + Control Data Functions + + + + + Function + + + Description + + + + + + + + + pg_control_checkpoint + + pg_control_checkpoint () + record + + + Returns information about current checkpoint state, as shown in + . + + + + + + + pg_control_system + + pg_control_system () + record + + + Returns information about current control file state, as shown in + . + + + + + + + pg_control_init + + pg_control_init () + record + + + Returns information about cluster initialization state, as shown in + . + + + + + + + pg_control_recovery + + pg_control_recovery () + record + + + Returns information about recovery state, as shown in + . + + + + +
+ + + <function>pg_control_checkpoint</function> Output Columns + + + + Column Name + Data Type + + + + + + + checkpoint_lsn + pg_lsn + + + + redo_lsn + pg_lsn + + + + redo_wal_file + text + + + + timeline_id + integer + + + + prev_timeline_id + integer + + + + full_page_writes + boolean + + + + next_xid + text + + + + next_oid + oid + + + + next_multixact_id + xid + + + + next_multi_offset + xid + + + + oldest_xid + xid + + + + oldest_xid_dbid + oid + + + + oldest_active_xid + xid + + + + oldest_multi_xid + xid + + + + oldest_multi_dbid + oid + + + + oldest_commit_ts_xid + xid + + + + newest_commit_ts_xid + xid + + + + checkpoint_time + timestamp with time zone + + + + +
+ + + <function>pg_control_system</function> Output Columns + + + + Column Name + Data Type + + + + + + + pg_control_version + integer + + + + catalog_version_no + integer + + + + system_identifier + bigint + + + + pg_control_last_modified + timestamp with time zone + + + + +
+ + + <function>pg_control_init</function> Output Columns + + + + Column Name + Data Type + + + + + + + max_data_alignment + integer + + + + database_block_size + integer + + + + blocks_per_segment + integer + + + + wal_block_size + integer + + + + bytes_per_wal_segment + integer + + + + max_identifier_length + integer + + + + max_index_columns + integer + + + + max_toast_chunk_size + integer + + + + large_object_chunk_size + integer + + + + float8_pass_by_value + boolean + + + + data_page_checksum_version + integer + + + + +
+ + + <function>pg_control_recovery</function> Output Columns + + + + Column Name + Data Type + + + + + + + min_recovery_end_lsn + pg_lsn + + + + min_recovery_end_timeline + integer + + + + backup_start_lsn + pg_lsn + + + + backup_end_lsn + pg_lsn + + + + end_of_backup_record_required + boolean + + + + +
+ + + + + Version Information Functions + + + The functions shown in + print version information. + + + + Version Information Functions + + + + + Function + + + Description + + + + + + + + + version + + version () + text + + + Returns a string describing the PostgreSQL + server's version. You can also get this information from + , or for a machine-readable + version use . Software + developers should use server_version_num (available + since 8.2) or instead of + parsing the text version. + + + + + + + unicode_version + + unicode_version () + text + + + Returns a string representing the version of Unicode used by + PostgreSQL. + + + + + + icu_unicode_version + + icu_unicode_version () + text + + + Returns a string representing the version of Unicode used by ICU, if + the server was built with ICU support; otherwise returns + NULL + + + +
+ + + + + WAL Summarization Information Functions + + + The functions shown in + print information about the status of WAL summarization. + See . + + + + WAL Summarization Information Functions + + + + + Function + + + Description + + + + + + + + + pg_available_wal_summaries + + pg_available_wal_summaries () + setof record + ( tli bigint, + start_lsn pg_lsn, + end_lsn pg_lsn ) + + + Returns information about the WAL summary files present in the + data directory, under pg_wal/summaries. + One row will be returned per WAL summary file. Each file summarizes + WAL on the indicated TLI within the indicated LSN range. This function + might be useful to determine whether enough WAL summaries are present + on the server to take an incremental backup based on some prior + backup whose start LSN is known. + + + + + + + pg_wal_summary_contents + + pg_wal_summary_contents ( tli bigint, start_lsn pg_lsn, end_lsn pg_lsn ) + setof record + ( relfilenode oid, + reltablespace oid, + reldatabase oid, + relforknumber smallint, + relblocknumber bigint, + is_limit_block boolean ) + + + Returns one information about the contents of a single WAL summary file + identified by TLI and starting and ending LSNs. Each row with + is_limit_block false indicates that the block + identified by the remaining output columns was modified by at least + one WAL record within the range of records summarized by this file. + Each row with is_limit_block true indicates either + that (a) the relation fork was truncated to the length given by + relblocknumber within the relevant range of WAL + records or (b) that the relation fork was created or dropped within + the relevant range of WAL records; in such cases, + relblocknumber will be zero. + + + + + + + pg_get_wal_summarizer_state + + pg_get_wal_summarizer_state () + record + ( summarized_tli bigint, + summarized_lsn pg_lsn, + pending_lsn pg_lsn, + summarizer_pid int ) + + + Returns information about the progress of the WAL summarizer. If the + WAL summarizer has never run since the instance was started, then + summarized_tli and summarized_lsn + will be 0 and 0/0 respectively; + otherwise, they will be the TLI and ending LSN of the last WAL summary + file written to disk. If the WAL summarizer is currently running, + pending_lsn will be the ending LSN of the last + record that it has consumed, which must always be greater than or + equal to summarized_lsn; if the WAL summarizer is + not running, it will be equal to summarized_lsn. + summarizer_pid is the PID of the WAL summarizer + process, if it is running, and otherwise NULL. + + + + +
+ + + + diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 8fd550ad..35a2d25b 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -12602,3646 +12602,7 @@ SELECT * FROM pg_ls_dir('.') WITH ORDINALITY AS t(ls,n); - - System Information Functions and Operators - - - The functions described in this section are used to obtain various - information about a PostgreSQL installation. - - - - Session Information Functions - - - shows several - functions that extract session and system information. - - - - In addition to the functions listed in this section, there are a number of - functions related to the statistics system that also provide system - information. See for more - information. - - - - Session Information Functions - - - - - Function - - - Description - - - - - - - - - current_catalog - - current_catalog - name - - - - current_database - - current_database () - name - - - Returns the name of the current database. (Databases are - called catalogs in the SQL standard, - so current_catalog is the standard's - spelling.) - - - - - - - current_query - - current_query () - text - - - Returns the text of the currently executing query, as submitted - by the client (which might contain more than one statement). - - - - - - - current_role - - current_role - name - - - This is equivalent to current_user. - - - - - - - current_schema - - - schema - current - - current_schema - name - - - current_schema () - name - - - Returns the name of the schema that is first in the search path (or a - null value if the search path is empty). This is the schema that will - be used for any tables or other named objects that are created without - specifying a target schema. - - - - - - - current_schemas - - - search path - current - - current_schemas ( include_implicit boolean ) - name[] - - - Returns an array of the names of all schemas presently in the - effective search path, in their priority order. (Items in the current - setting that do not correspond to - existing, searchable schemas are omitted.) If the Boolean argument - is true, then implicitly-searched system schemas - such as pg_catalog are included in the result. - - - - - - - current_user - - - user - current - - current_user - name - - - Returns the user name of the current execution context. - - - - - - - inet_client_addr - - inet_client_addr () - inet - - - Returns the IP address of the current client, - or NULL if the current connection is via a - Unix-domain socket. - - - - - - - inet_client_port - - inet_client_port () - integer - - - Returns the IP port number of the current client, - or NULL if the current connection is via a - Unix-domain socket. - - - - - - - inet_server_addr - - inet_server_addr () - inet - - - Returns the IP address on which the server accepted the current - connection, - or NULL if the current connection is via a - Unix-domain socket. - - - - - - - inet_server_port - - inet_server_port () - integer - - - Returns the IP port number on which the server accepted the current - connection, - or NULL if the current connection is via a - Unix-domain socket. - - - - - - - pg_backend_pid - - pg_backend_pid () - integer - - - Returns the process ID of the server process attached to the current - session. - - - - - - - pg_blocking_pids - - pg_blocking_pids ( integer ) - integer[] - - - Returns an array of the process ID(s) of the sessions that are - blocking the server process with the specified process ID from - acquiring a lock, or an empty array if there is no such server process - or it is not blocked. - - - One server process blocks another if it either holds a lock that - conflicts with the blocked process's lock request (hard block), or is - waiting for a lock that would conflict with the blocked process's lock - request and is ahead of it in the wait queue (soft block). When using - parallel queries the result always lists client-visible process IDs - (that is, pg_backend_pid results) even if the - actual lock is held or awaited by a child worker process. As a result - of that, there may be duplicated PIDs in the result. Also note that - when a prepared transaction holds a conflicting lock, it will be - represented by a zero process ID. - - - Frequent calls to this function could have some impact on database - performance, because it needs exclusive access to the lock manager's - shared state for a short time. - - - - - - - pg_conf_load_time - - pg_conf_load_time () - timestamp with time zone - - - Returns the time when the server configuration files were last loaded. - If the current session was alive at the time, this will be the time - when the session itself re-read the configuration files (so the - reading will vary a little in different sessions). Otherwise it is - the time when the postmaster process re-read the configuration files. - - - - - - - pg_current_logfile - - - Logging - pg_current_logfile function - - - current_logfiles - and the pg_current_logfile function - - - Logging - current_logfiles file and the pg_current_logfile - function - - pg_current_logfile ( text ) - text - - - Returns the path name of the log file currently in use by the logging - collector. The path includes the - directory and the individual log file name. The result - is NULL if the logging collector is disabled. - When multiple log files exist, each in a different - format, pg_current_logfile without an argument - returns the path of the file having the first format found in the - ordered list: stderr, - csvlog, jsonlog. - NULL is returned if no log file has any of these - formats. - To request information about a specific log file format, supply - either csvlog, jsonlog or - stderr as the - value of the optional parameter. The result is NULL - if the log format requested is not configured in - . - The result reflects the contents of - the current_logfiles file. - - - This function is restricted to superusers and roles with privileges of - the pg_monitor role by default, but other users can - be granted EXECUTE to run the function. - - - - - - - pg_my_temp_schema - - pg_my_temp_schema () - oid - - - Returns the OID of the current session's temporary schema, or zero if - it has none (because it has not created any temporary tables). - - - - - - - pg_is_other_temp_schema - - pg_is_other_temp_schema ( oid ) - boolean - - - Returns true if the given OID is the OID of another session's - temporary schema. (This can be useful, for example, to exclude other - sessions' temporary tables from a catalog display.) - - - - - - - pg_jit_available - - pg_jit_available () - boolean - - - Returns true if a JIT compiler extension is - available (see ) and the - configuration parameter is set to - on. - - - - - - - pg_listening_channels - - pg_listening_channels () - setof text - - - Returns the set of names of asynchronous notification channels that - the current session is listening to. - - - - - - - pg_notification_queue_usage - - pg_notification_queue_usage () - double precision - - - Returns the fraction (0–1) of the asynchronous notification - queue's maximum size that is currently occupied by notifications that - are waiting to be processed. - See and - for more information. - - - - - - - pg_postmaster_start_time - - pg_postmaster_start_time () - timestamp with time zone - - - Returns the time when the server started. - - - - - - - pg_safe_snapshot_blocking_pids - - pg_safe_snapshot_blocking_pids ( integer ) - integer[] - - - Returns an array of the process ID(s) of the sessions that are blocking - the server process with the specified process ID from acquiring a safe - snapshot, or an empty array if there is no such server process or it - is not blocked. - - - A session running a SERIALIZABLE transaction blocks - a SERIALIZABLE READ ONLY DEFERRABLE transaction - from acquiring a snapshot until the latter determines that it is safe - to avoid taking any predicate locks. See - for more information about - serializable and deferrable transactions. - - - Frequent calls to this function could have some impact on database - performance, because it needs access to the predicate lock manager's - shared state for a short time. - - - - - - - pg_trigger_depth - - pg_trigger_depth () - integer - - - Returns the current nesting level - of PostgreSQL triggers (0 if not called, - directly or indirectly, from inside a trigger). - - - - - - - session_user - - session_user - name - - - Returns the session user's name. - - - - - - - system_user - - system_user - text - - - Returns the authentication method and the identity (if any) that the - user presented during the authentication cycle before they were - assigned a database role. It is represented as - auth_method:identity or - NULL if the user has not been authenticated (for - example if Trust authentication has - been used). - - - - - - - user - - user - name - - - This is equivalent to current_user. - - - - -
- - - - current_catalog, - current_role, - current_schema, - current_user, - session_user, - and user have special syntactic status - in SQL: they must be called without trailing - parentheses. In PostgreSQL, parentheses can optionally be used with - current_schema, but not with the others. - - - - - The session_user is normally the user who initiated - the current database connection; but superusers can change this setting - with . - The current_user is the user identifier - that is applicable for permission checking. Normally it is equal - to the session user, but it can be changed with - . - It also changes during the execution of - functions with the attribute SECURITY DEFINER. - In Unix parlance, the session user is the real user and - the current user is the effective user. - current_role and user are - synonyms for current_user. (The SQL standard draws - a distinction between current_role - and current_user, but PostgreSQL - does not, since it unifies users and roles into a single kind of entity.) - - - - - - Access Privilege Inquiry Functions - - - privilege - querying - - - - lists functions that - allow querying object access privileges programmatically. - (See for more information about - privileges.) - In these functions, the user whose privileges are being inquired about - can be specified by name or by OID - (pg_authid.oid), or if - the name is given as public then the privileges of the - PUBLIC pseudo-role are checked. Also, the user - argument can be omitted entirely, in which case - the current_user is assumed. - The object that is being inquired about can be specified either by name or - by OID, too. When specifying by name, a schema name can be included if - relevant. - The access privilege of interest is specified by a text string, which must - evaluate to one of the appropriate privilege keywords for the object's type - (e.g., SELECT). Optionally, WITH GRANT - OPTION can be added to a privilege type to test whether the - privilege is held with grant option. Also, multiple privilege types can be - listed separated by commas, in which case the result will be true if any of - the listed privileges is held. (Case of the privilege string is not - significant, and extra whitespace is allowed between but not within - privilege names.) - Some examples: - -SELECT has_table_privilege('myschema.mytable', 'select'); -SELECT has_table_privilege('joe', 'mytable', 'INSERT, SELECT WITH GRANT OPTION'); - - - - - Access Privilege Inquiry Functions - - - - - Function - - - Description - - - - - - - - - has_any_column_privilege - - has_any_column_privilege ( - user name or oid, - table text or oid, - privilege text ) - boolean - - - Does user have privilege for any column of table? - This succeeds either if the privilege is held for the whole table, or - if there is a column-level grant of the privilege for at least one - column. - Allowable privilege types are - SELECT, INSERT, - UPDATE, and REFERENCES. - - - - - - - has_column_privilege - - has_column_privilege ( - user name or oid, - table text or oid, - column text or smallint, - privilege text ) - boolean - - - Does user have privilege for the specified table column? - This succeeds either if the privilege is held for the whole table, or - if there is a column-level grant of the privilege for the column. - The column can be specified by name or by attribute number - (pg_attribute.attnum). - Allowable privilege types are - SELECT, INSERT, - UPDATE, and REFERENCES. - - - - - - - has_database_privilege - - has_database_privilege ( - user name or oid, - database text or oid, - privilege text ) - boolean - - - Does user have privilege for database? - Allowable privilege types are - CREATE, - CONNECT, - TEMPORARY, and - TEMP (which is equivalent to - TEMPORARY). - - - - - - - has_foreign_data_wrapper_privilege - - has_foreign_data_wrapper_privilege ( - user name or oid, - fdw text or oid, - privilege text ) - boolean - - - Does user have privilege for foreign-data wrapper? - The only allowable privilege type is USAGE. - - - - - - - has_function_privilege - - has_function_privilege ( - user name or oid, - function text or oid, - privilege text ) - boolean - - - Does user have privilege for function? - The only allowable privilege type is EXECUTE. - - - When specifying a function by name rather than by OID, the allowed - input is the same as for the regprocedure data type (see - ). - An example is: - -SELECT has_function_privilege('joeuser', 'myfunc(int, text)', 'execute'); - - - - - - - - has_language_privilege - - has_language_privilege ( - user name or oid, - language text or oid, - privilege text ) - boolean - - - Does user have privilege for language? - The only allowable privilege type is USAGE. - - - - - - - has_parameter_privilege - - has_parameter_privilege ( - user name or oid, - parameter text, - privilege text ) - boolean - - - Does user have privilege for configuration parameter? - The parameter name is case-insensitive. - Allowable privilege types are SET - and ALTER SYSTEM. - - - - - - - has_schema_privilege - - has_schema_privilege ( - user name or oid, - schema text or oid, - privilege text ) - boolean - - - Does user have privilege for schema? - Allowable privilege types are - CREATE and - USAGE. - - - - - - - has_sequence_privilege - - has_sequence_privilege ( - user name or oid, - sequence text or oid, - privilege text ) - boolean - - - Does user have privilege for sequence? - Allowable privilege types are - USAGE, - SELECT, and - UPDATE. - - - - - - - has_server_privilege - - has_server_privilege ( - user name or oid, - server text or oid, - privilege text ) - boolean - - - Does user have privilege for foreign server? - The only allowable privilege type is USAGE. - - - - - - - has_table_privilege - - has_table_privilege ( - user name or oid, - table text or oid, - privilege text ) - boolean - - - Does user have privilege for table? - Allowable privilege types - are SELECT, INSERT, - UPDATE, DELETE, - TRUNCATE, REFERENCES, - TRIGGER, and MAINTAIN. - - - - - - - has_tablespace_privilege - - has_tablespace_privilege ( - user name or oid, - tablespace text or oid, - privilege text ) - boolean - - - Does user have privilege for tablespace? - The only allowable privilege type is CREATE. - - - - - - - has_type_privilege - - has_type_privilege ( - user name or oid, - type text or oid, - privilege text ) - boolean - - - Does user have privilege for data type? - The only allowable privilege type is USAGE. - When specifying a type by name rather than by OID, the allowed input - is the same as for the regtype data type (see - ). - - - - - - - pg_has_role - - pg_has_role ( - user name or oid, - role text or oid, - privilege text ) - boolean - - - Does user have privilege for role? - Allowable privilege types are - MEMBER, USAGE, - and SET. - MEMBER denotes direct or indirect membership in - the role without regard to what specific privileges may be conferred. - USAGE denotes whether the privileges of the role - are immediately available without doing SET ROLE, - while SET denotes whether it is possible to change - to the role using the SET ROLE command. - This function does not allow the special case of - setting user to public, - because the PUBLIC pseudo-role can never be a member of real roles. - - - - - - - row_security_active - - row_security_active ( - table text or oid ) - boolean - - - Is row-level security active for the specified table in the context of - the current user and current environment? - - - - -
- - - shows the operators - available for the aclitem type, which is the catalog - representation of access privileges. See - for information about how to read access privilege values. - - - - <type>aclitem</type> Operators - - - - - Operator - - - Description - - - Example(s) - - - - - - - - - aclitemeq - - aclitem = aclitem - boolean - - - Are aclitems equal? (Notice that - type aclitem lacks the usual set of comparison - operators; it has only equality. In turn, aclitem - arrays can only be compared for equality.) - - - 'calvin=r*w/hobbes'::aclitem = 'calvin=r*w*/hobbes'::aclitem - f - - - - - - - aclcontains - - aclitem[] @> aclitem - boolean - - - Does array contain the specified privileges? (This is true if there - is an array entry that matches the aclitem's grantee and - grantor, and has at least the specified set of privileges.) - - - '{calvin=r*w/hobbes,hobbes=r*w*/postgres}'::aclitem[] @> 'calvin=r*/hobbes'::aclitem - t - - - - - - aclitem[] ~ aclitem - boolean - - - This is a deprecated alias for @>. - - - '{calvin=r*w/hobbes,hobbes=r*w*/postgres}'::aclitem[] ~ 'calvin=r*/hobbes'::aclitem - t - - - - -
- - - shows some additional - functions to manage the aclitem type. - - - - <type>aclitem</type> Functions - - - - - Function - - - Description - - - - - - - - - acldefault - - acldefault ( - type "char", - ownerId oid ) - aclitem[] - - - Constructs an aclitem array holding the default access - privileges for an object of type type belonging - to the role with OID ownerId. This represents - the access privileges that will be assumed when an object's ACL entry - is null. (The default access privileges are described in - .) - The type parameter must be one of - 'c' for COLUMN, - 'r' for TABLE and table-like objects, - 's' for SEQUENCE, - 'd' for DATABASE, - 'f' for FUNCTION or PROCEDURE, - 'l' for LANGUAGE, - 'L' for LARGE OBJECT, - 'n' for SCHEMA, - 'p' for PARAMETER, - 't' for TABLESPACE, - 'F' for FOREIGN DATA WRAPPER, - 'S' for FOREIGN SERVER, - or - 'T' for TYPE or DOMAIN. - - - - - - - aclexplode - - aclexplode ( aclitem[] ) - setof record - ( grantor oid, - grantee oid, - privilege_type text, - is_grantable boolean ) - - - Returns the aclitem array as a set of rows. - If the grantee is the pseudo-role PUBLIC, it is represented by zero in - the grantee column. Each granted privilege is - represented as SELECT, INSERT, - etc (see for a full list). - Note that each privilege is broken out as a separate row, so - only one keyword appears in the privilege_type - column. - - - - - - - makeaclitem - - makeaclitem ( - grantee oid, - grantor oid, - privileges text, - is_grantable boolean ) - aclitem - - - Constructs an aclitem with the given properties. - privileges is a comma-separated list of - privilege names such as SELECT, - INSERT, etc, all of which are set in the - result. (Case of the privilege string is not significant, and - extra whitespace is allowed between but not within privilege - names.) - - - - -
- - - - - Schema Visibility Inquiry Functions - - - shows functions that - determine whether a certain object is visible in the - current schema search path. - For example, a table is said to be visible if its - containing schema is in the search path and no table of the same - name appears earlier in the search path. This is equivalent to the - statement that the table can be referenced by name without explicit - schema qualification. Thus, to list the names of all visible tables: - -SELECT relname FROM pg_class WHERE pg_table_is_visible(oid); - - For functions and operators, an object in the search path is said to be - visible if there is no object of the same name and argument data - type(s) earlier in the path. For operator classes and families, - both the name and the associated index access method are considered. - - - - search path - object visibility - - - - Schema Visibility Inquiry Functions - - - - - Function - - - Description - - - - - - - - - pg_collation_is_visible - - pg_collation_is_visible ( collation oid ) - boolean - - - Is collation visible in search path? - - - - - - - pg_conversion_is_visible - - pg_conversion_is_visible ( conversion oid ) - boolean - - - Is conversion visible in search path? - - - - - - - pg_function_is_visible - - pg_function_is_visible ( function oid ) - boolean - - - Is function visible in search path? - (This also works for procedures and aggregates.) - - - - - - - pg_opclass_is_visible - - pg_opclass_is_visible ( opclass oid ) - boolean - - - Is operator class visible in search path? - - - - - - - pg_operator_is_visible - - pg_operator_is_visible ( operator oid ) - boolean - - - Is operator visible in search path? - - - - - - - pg_opfamily_is_visible - - pg_opfamily_is_visible ( opclass oid ) - boolean - - - Is operator family visible in search path? - - - - - - - pg_statistics_obj_is_visible - - pg_statistics_obj_is_visible ( stat oid ) - boolean - - - Is statistics object visible in search path? - - - - - - - pg_table_is_visible - - pg_table_is_visible ( table oid ) - boolean - - - Is table visible in search path? - (This works for all types of relations, including views, materialized - views, indexes, sequences and foreign tables.) - - - - - - - pg_ts_config_is_visible - - pg_ts_config_is_visible ( config oid ) - boolean - - - Is text search configuration visible in search path? - - - - - - - pg_ts_dict_is_visible - - pg_ts_dict_is_visible ( dict oid ) - boolean - - - Is text search dictionary visible in search path? - - - - - - - pg_ts_parser_is_visible - - pg_ts_parser_is_visible ( parser oid ) - boolean - - - Is text search parser visible in search path? - - - - - - - pg_ts_template_is_visible - - pg_ts_template_is_visible ( template oid ) - boolean - - - Is text search template visible in search path? - - - - - - - pg_type_is_visible - - pg_type_is_visible ( type oid ) - boolean - - - Is type (or domain) visible in search path? - - - - -
- - - All these functions require object OIDs to identify the object to be - checked. If you want to test an object by name, it is convenient to use - the OID alias types (regclass, regtype, - regprocedure, regoperator, regconfig, - or regdictionary), - for example: - -SELECT pg_type_is_visible('myschema.widget'::regtype); - - Note that it would not make much sense to test a non-schema-qualified - type name in this way — if the name can be recognized at all, it must be visible. - - - - - - System Catalog Information Functions - - - lists functions that - extract information from the system catalogs. - - - - System Catalog Information Functions - - - - - Function - - - Description - - - - - - - - - format_type - - format_type ( type oid, typemod integer ) - text - - - Returns the SQL name for a data type that is identified by its type - OID and possibly a type modifier. Pass NULL for the type modifier if - no specific modifier is known. - - - - - - - pg_basetype - - pg_basetype ( regtype ) - regtype - - - Returns the OID of the base type of a domain identified by its - type OID. If the argument is the OID of a non-domain type, - returns the argument as-is. Returns NULL if the argument is - not a valid type OID. If there's a chain of domain dependencies, - it will recurse until finding the base type. - - - Assuming CREATE DOMAIN mytext AS text: - - - pg_basetype('mytext'::regtype) - text - - - - - - - pg_char_to_encoding - - pg_char_to_encoding ( encoding name ) - integer - - - Converts the supplied encoding name into an integer representing the - internal identifier used in some system catalog tables. - Returns -1 if an unknown encoding name is provided. - - - - - - - pg_encoding_to_char - - pg_encoding_to_char ( encoding integer ) - name - - - Converts the integer used as the internal identifier of an encoding in some - system catalog tables into a human-readable string. - Returns an empty string if an invalid encoding number is provided. - - - - - - - pg_get_catalog_foreign_keys - - pg_get_catalog_foreign_keys () - setof record - ( fktable regclass, - fkcols text[], - pktable regclass, - pkcols text[], - is_array boolean, - is_opt boolean ) - - - Returns a set of records describing the foreign key relationships - that exist within the PostgreSQL system - catalogs. - The fktable column contains the name of the - referencing catalog, and the fkcols column - contains the name(s) of the referencing column(s). Similarly, - the pktable column contains the name of the - referenced catalog, and the pkcols column - contains the name(s) of the referenced column(s). - If is_array is true, the last referencing - column is an array, each of whose elements should match some entry - in the referenced catalog. - If is_opt is true, the referencing column(s) - are allowed to contain zeroes instead of a valid reference. - - - - - - - pg_get_constraintdef - - pg_get_constraintdef ( constraint oid , pretty boolean ) - text - - - Reconstructs the creating command for a constraint. - (This is a decompiled reconstruction, not the original text - of the command.) - - - - - - - pg_get_expr - - pg_get_expr ( expr pg_node_tree, relation oid , pretty boolean ) - text - - - Decompiles the internal form of an expression stored in the system - catalogs, such as the default value for a column. If the expression - might contain Vars, specify the OID of the relation they refer to as - the second parameter; if no Vars are expected, passing zero is - sufficient. - - - - - - - pg_get_functiondef - - pg_get_functiondef ( func oid ) - text - - - Reconstructs the creating command for a function or procedure. - (This is a decompiled reconstruction, not the original text - of the command.) - The result is a complete CREATE OR REPLACE FUNCTION - or CREATE OR REPLACE PROCEDURE statement. - - - - - - - pg_get_function_arguments - - pg_get_function_arguments ( func oid ) - text - - - Reconstructs the argument list of a function or procedure, in the form - it would need to appear in within CREATE FUNCTION - (including default values). - - - - - - - pg_get_function_identity_arguments - - pg_get_function_identity_arguments ( func oid ) - text - - - Reconstructs the argument list necessary to identify a function or - procedure, in the form it would need to appear in within commands such - as ALTER FUNCTION. This form omits default values. - - - - - - - pg_get_function_result - - pg_get_function_result ( func oid ) - text - - - Reconstructs the RETURNS clause of a function, in - the form it would need to appear in within CREATE - FUNCTION. Returns NULL for a procedure. - - - - - - - pg_get_indexdef - - pg_get_indexdef ( index oid , column integer, pretty boolean ) - text - - - Reconstructs the creating command for an index. - (This is a decompiled reconstruction, not the original text - of the command.) If column is supplied and is - not zero, only the definition of that column is reconstructed. - - - - - - - pg_get_keywords - - pg_get_keywords () - setof record - ( word text, - catcode "char", - barelabel boolean, - catdesc text, - baredesc text ) - - - Returns a set of records describing the SQL keywords recognized by the - server. The word column contains the - keyword. The catcode column contains a - category code: U for an unreserved - keyword, C for a keyword that can be a column - name, T for a keyword that can be a type or - function name, or R for a fully reserved keyword. - The barelabel column - contains true if the keyword can be used as - a bare column label in SELECT lists, - or false if it can only be used - after AS. - The catdesc column contains a - possibly-localized string describing the keyword's category. - The baredesc column contains a - possibly-localized string describing the keyword's column label status. - - - - - - - pg_get_partkeydef - - pg_get_partkeydef ( table oid ) - text - - - Reconstructs the definition of a partitioned table's partition - key, in the form it would have in the PARTITION - BY clause of CREATE TABLE. - (This is a decompiled reconstruction, not the original text - of the command.) - - - - - - - pg_get_ruledef - - pg_get_ruledef ( rule oid , pretty boolean ) - text - - - Reconstructs the creating command for a rule. - (This is a decompiled reconstruction, not the original text - of the command.) - - - - - - - pg_get_serial_sequence - - pg_get_serial_sequence ( table text, column text ) - text - - - Returns the name of the sequence associated with a column, - or NULL if no sequence is associated with the column. - If the column is an identity column, the associated sequence is the - sequence internally created for that column. - For columns created using one of the serial types - (serial, smallserial, bigserial), - it is the sequence created for that serial column definition. - In the latter case, the association can be modified or removed - with ALTER SEQUENCE OWNED BY. - (This function probably should have been - called pg_get_owned_sequence; its current name - reflects the fact that it has historically been used with serial-type - columns.) The first parameter is a table name with optional - schema, and the second parameter is a column name. Because the first - parameter potentially contains both schema and table names, it is - parsed per usual SQL rules, meaning it is lower-cased by default. - The second parameter, being just a column name, is treated literally - and so has its case preserved. The result is suitably formatted - for passing to the sequence functions (see - ). - - - A typical use is in reading the current value of the sequence for an - identity or serial column, for example: - -SELECT currval(pg_get_serial_sequence('sometable', 'id')); - - - - - - - - pg_get_statisticsobjdef - - pg_get_statisticsobjdef ( statobj oid ) - text - - - Reconstructs the creating command for an extended statistics object. - (This is a decompiled reconstruction, not the original text - of the command.) - - - - - - - pg_get_triggerdef - -pg_get_triggerdef ( trigger oid , pretty boolean ) - text - - - Reconstructs the creating command for a trigger. - (This is a decompiled reconstruction, not the original text - of the command.) - - - - - - - pg_get_userbyid - - pg_get_userbyid ( role oid ) - name - - - Returns a role's name given its OID. - - - - - - - pg_get_viewdef - - pg_get_viewdef ( view oid , pretty boolean ) - text - - - Reconstructs the underlying SELECT command for a - view or materialized view. (This is a decompiled reconstruction, not - the original text of the command.) - - - - - - pg_get_viewdef ( view oid, wrap_column integer ) - text - - - Reconstructs the underlying SELECT command for a - view or materialized view. (This is a decompiled reconstruction, not - the original text of the command.) In this form of the function, - pretty-printing is always enabled, and long lines are wrapped to try - to keep them shorter than the specified number of columns. - - - - - - pg_get_viewdef ( view text , pretty boolean ) - text - - - Reconstructs the underlying SELECT command for a - view or materialized view, working from a textual name for the view - rather than its OID. (This is deprecated; use the OID variant - instead.) - - - - - - - pg_index_column_has_property - - pg_index_column_has_property ( index regclass, column integer, property text ) - boolean - - - Tests whether an index column has the named property. - Common index column properties are listed in - . - (Note that extension access methods can define additional property - names for their indexes.) - NULL is returned if the property name is not known - or does not apply to the particular object, or if the OID or column - number does not identify a valid object. - - - - - - - pg_index_has_property - - pg_index_has_property ( index regclass, property text ) - boolean - - - Tests whether an index has the named property. - Common index properties are listed in - . - (Note that extension access methods can define additional property - names for their indexes.) - NULL is returned if the property name is not known - or does not apply to the particular object, or if the OID does not - identify a valid object. - - - - - - - pg_indexam_has_property - - pg_indexam_has_property ( am oid, property text ) - boolean - - - Tests whether an index access method has the named property. - Access method properties are listed in - . - NULL is returned if the property name is not known - or does not apply to the particular object, or if the OID does not - identify a valid object. - - - - - - - pg_options_to_table - - pg_options_to_table ( options_array text[] ) - setof record - ( option_name text, - option_value text ) - - - Returns the set of storage options represented by a value from - pg_class.reloptions or - pg_attribute.attoptions. - - - - - - - pg_settings_get_flags - - pg_settings_get_flags ( guc text ) - text[] - - - Returns an array of the flags associated with the given GUC, or - NULL if it does not exist. The result is - an empty array if the GUC exists but there are no flags to show. - Only the most useful flags listed in - are exposed. - - - - - - - pg_tablespace_databases - - pg_tablespace_databases ( tablespace oid ) - setof oid - - - Returns the set of OIDs of databases that have objects stored in the - specified tablespace. If this function returns any rows, the - tablespace is not empty and cannot be dropped. To identify the specific - objects populating the tablespace, you will need to connect to the - database(s) identified by pg_tablespace_databases - and query their pg_class catalogs. - - - - - - - pg_tablespace_location - - pg_tablespace_location ( tablespace oid ) - text - - - Returns the file system path that this tablespace is located in. - - - - - - - pg_typeof - - pg_typeof ( "any" ) - regtype - - - Returns the OID of the data type of the value that is passed to it. - This can be helpful for troubleshooting or dynamically constructing - SQL queries. The function is declared as - returning regtype, which is an OID alias type (see - ); this means that it is the same as an - OID for comparison purposes but displays as a type name. - - - pg_typeof(33) - integer - - - - - - - COLLATION FOR - - COLLATION FOR ( "any" ) - text - - - Returns the name of the collation of the value that is passed to it. - The value is quoted and schema-qualified if necessary. If no - collation was derived for the argument expression, - then NULL is returned. If the argument is not of a - collatable data type, then an error is raised. - - - collation for ('foo'::text) - "default" - - - collation for ('foo' COLLATE "de_DE") - "de_DE" - - - - - - - to_regclass - - to_regclass ( text ) - regclass - - - Translates a textual relation name to its OID. A similar result is - obtained by casting the string to type regclass (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found. - - - - - - - to_regcollation - - to_regcollation ( text ) - regcollation - - - Translates a textual collation name to its OID. A similar result is - obtained by casting the string to type regcollation (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found. - - - - - - - to_regnamespace - - to_regnamespace ( text ) - regnamespace - - - Translates a textual schema name to its OID. A similar result is - obtained by casting the string to type regnamespace (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found. - - - - - - - to_regoper - - to_regoper ( text ) - regoper - - - Translates a textual operator name to its OID. A similar result is - obtained by casting the string to type regoper (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found or is ambiguous. - - - - - - - to_regoperator - - to_regoperator ( text ) - regoperator - - - Translates a textual operator name (with parameter types) to its OID. A similar result is - obtained by casting the string to type regoperator (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found. - - - - - - - to_regproc - - to_regproc ( text ) - regproc - - - Translates a textual function or procedure name to its OID. A similar result is - obtained by casting the string to type regproc (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found or is ambiguous. - - - - - - - to_regprocedure - - to_regprocedure ( text ) - regprocedure - - - Translates a textual function or procedure name (with argument types) to its OID. A similar result is - obtained by casting the string to type regprocedure (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found. - - - - - - - to_regrole - - to_regrole ( text ) - regrole - - - Translates a textual role name to its OID. A similar result is - obtained by casting the string to type regrole (see - ); however, this function will return - NULL rather than throwing an error if the name is - not found. - - - - - - - to_regtype - - to_regtype ( text ) - regtype - - - Parses a string of text, extracts a potential type name from it, - and translates that name into a type OID. A syntax error in the - string will result in an error; but if the string is a - syntactically valid type name that happens not to be found in the - catalogs, the result is NULL. A similar result - is obtained by casting the string to type regtype - (see ), except that that will throw - error for name not found. - - - - - - - to_regtypemod - - to_regtypemod ( text ) - integer - - - Parses a string of text, extracts a potential type name from it, - and translates its type modifier, if any. A syntax error in the - string will result in an error; but if the string is a - syntactically valid type name that happens not to be found in the - catalogs, the result is NULL. The result is - -1 if no type modifier is present. - - - to_regtypemod can be combined with - to produce appropriate inputs for - , allowing a string representing a - type name to be canonicalized. - - - format_type(to_regtype('varchar(32)'), to_regtypemod('varchar(32)')) - character varying(32) - - - - -
- - - Most of the functions that reconstruct (decompile) database objects - have an optional pretty flag, which - if true causes the result to - be pretty-printed. Pretty-printing suppresses unnecessary - parentheses and adds whitespace for legibility. - The pretty-printed format is more readable, but the default format - is more likely to be interpreted the same way by future versions of - PostgreSQL; so avoid using pretty-printed output - for dump purposes. Passing false for - the pretty parameter yields the same result as - omitting the parameter. - - - - Index Column Properties - - - NameDescription - - - - asc - Does the column sort in ascending order on a forward scan? - - - - desc - Does the column sort in descending order on a forward scan? - - - - nulls_first - Does the column sort with nulls first on a forward scan? - - - - nulls_last - Does the column sort with nulls last on a forward scan? - - - - orderable - Does the column possess any defined sort ordering? - - - - distance_orderable - Can the column be scanned in order by a distance - operator, for example ORDER BY col <-> constant ? - - - - returnable - Can the column value be returned by an index-only scan? - - - - search_array - Does the column natively support col = ANY(array) - searches? - - - - search_nulls - Does the column support IS NULL and - IS NOT NULL searches? - - - - -
- - - Index Properties - - - NameDescription - - - - clusterable - Can the index be used in a CLUSTER command? - - - - index_scan - Does the index support plain (non-bitmap) scans? - - - - bitmap_scan - Does the index support bitmap scans? - - - - backward_scan - Can the scan direction be changed in mid-scan (to - support FETCH BACKWARD on a cursor without - needing materialization)? - - - - -
- - - Index Access Method Properties - - - NameDescription - - - - can_order - Does the access method support ASC, - DESC and related keywords in - CREATE INDEX? - - - - can_unique - Does the access method support unique indexes? - - - - can_multi_col - Does the access method support indexes with multiple columns? - - - - can_exclude - Does the access method support exclusion constraints? - - - - can_include - Does the access method support the INCLUDE - clause of CREATE INDEX? - - - - -
- - - GUC Flags - - - FlagDescription - - - - EXPLAIN - Parameters with this flag are included in - EXPLAIN (SETTINGS) commands. - - - - NO_SHOW_ALL - Parameters with this flag are excluded from - SHOW ALL commands. - - - - NO_RESET - Parameters with this flag do not support - RESET commands. - - - - NO_RESET_ALL - Parameters with this flag are excluded from - RESET ALL commands. - - - - NOT_IN_SAMPLE - Parameters with this flag are not included in - postgresql.conf by default. - - - - RUNTIME_COMPUTED - Parameters with this flag are runtime-computed ones. - - - - -
- - - - - Object Information and Addressing Functions - - - lists functions related to - database object identification and addressing. - - - - Object Information and Addressing Functions - - - - - Function - - - Description - - - - - - - - - pg_describe_object - - pg_describe_object ( classid oid, objid oid, objsubid integer ) - text - - - Returns a textual description of a database object identified by - catalog OID, object OID, and sub-object ID (such as a column number - within a table; the sub-object ID is zero when referring to a whole - object). This description is intended to be human-readable, and might - be translated, depending on server configuration. This is especially - useful to determine the identity of an object referenced in the - pg_depend catalog. This function returns - NULL values for undefined objects. - - - - - - - pg_identify_object - - pg_identify_object ( classid oid, objid oid, objsubid integer ) - record - ( type text, - schema text, - name text, - identity text ) - - - Returns a row containing enough information to uniquely identify the - database object specified by catalog OID, object OID and sub-object - ID. - This information is intended to be machine-readable, and is never - translated. - type identifies the type of database object; - schema is the schema name that the object - belongs in, or NULL for object types that do not - belong to schemas; - name is the name of the object, quoted if - necessary, if the name (along with schema name, if pertinent) is - sufficient to uniquely identify the object, - otherwise NULL; - identity is the complete object identity, with - the precise format depending on object type, and each name within the - format being schema-qualified and quoted as necessary. Undefined - objects are identified with NULL values. - - - - - - - pg_identify_object_as_address - - pg_identify_object_as_address ( classid oid, objid oid, objsubid integer ) - record - ( type text, - object_names text[], - object_args text[] ) - - - Returns a row containing enough information to uniquely identify the - database object specified by catalog OID, object OID and sub-object - ID. - The returned information is independent of the current server, that - is, it could be used to identify an identically named object in - another server. - type identifies the type of database object; - object_names and - object_args - are text arrays that together form a reference to the object. - These three values can be passed - to pg_get_object_address to obtain the internal - address of the object. - - - - - - - pg_get_object_address - - pg_get_object_address ( type text, object_names text[], object_args text[] ) - record - ( classid oid, - objid oid, - objsubid integer ) - - - Returns a row containing enough information to uniquely identify the - database object specified by a type code and object name and argument - arrays. - The returned values are the ones that would be used in system catalogs - such as pg_depend; they can be passed to - other system functions such as pg_describe_object - or pg_identify_object. - classid is the OID of the system catalog - containing the object; - objid is the OID of the object itself, and - objsubid is the sub-object ID, or zero if none. - This function is the inverse - of pg_identify_object_as_address. - Undefined objects are identified with NULL values. - - - - -
- - - - - Comment Information Functions - - - comment - about database objects - - - - The functions shown in - extract comments previously stored with the - command. A null value is returned if no - comment could be found for the specified parameters. - - - - Comment Information Functions - - - - - Function - - - Description - - - - - - - - - col_description - - col_description ( table oid, column integer ) - text - - - Returns the comment for a table column, which is specified by the OID - of its table and its column number. - (obj_description cannot be used for table - columns, since columns do not have OIDs of their own.) - - - - - - - obj_description - - obj_description ( object oid, catalog name ) - text - - - Returns the comment for a database object specified by its OID and the - name of the containing system catalog. For - example, obj_description(123456, 'pg_class') would - retrieve the comment for the table with OID 123456. - - - - - - obj_description ( object oid ) - text - - - Returns the comment for a database object specified by its OID alone. - This is deprecated since there is no guarantee - that OIDs are unique across different system catalogs; therefore, the - wrong comment might be returned. - - - - - - - shobj_description - - shobj_description ( object oid, catalog name ) - text - - - Returns the comment for a shared database object specified by its OID - and the name of the containing system catalog. This is just - like obj_description except that it is used for - retrieving comments on shared objects (that is, databases, roles, and - tablespaces). Some system catalogs are global to all databases within - each cluster, and the descriptions for objects in them are stored - globally as well. - - - - -
- - - - - Data Validity Checking Functions - - - The functions shown in - can be helpful for checking validity of proposed input data. - - - - Data Validity Checking Functions - - - - - Function - - - Description - - - Example(s) - - - - - - - - - pg_input_is_valid - - pg_input_is_valid ( - string text, - type text - ) - boolean - - - Tests whether the given string is valid - input for the specified data type, returning true or false. - - - This function will only work as desired if the data type's input - function has been updated to report invalid input as - a soft error. Otherwise, invalid input will abort - the transaction, just as if the string had been cast to the type - directly. - - - pg_input_is_valid('42', 'integer') - t - - - pg_input_is_valid('42000000000', 'integer') - f - - - pg_input_is_valid('1234.567', 'numeric(7,4)') - f - - - - - - pg_input_error_info - - pg_input_error_info ( - string text, - type text - ) - record - ( message text, - detail text, - hint text, - sql_error_code text ) - - - Tests whether the given string is valid - input for the specified data type; if not, return the details of - the error that would have been thrown. If the input is valid, the - results are NULL. The inputs are the same as - for pg_input_is_valid. - - - This function will only work as desired if the data type's input - function has been updated to report invalid input as - a soft error. Otherwise, invalid input will abort - the transaction, just as if the string had been cast to the type - directly. - - - select * from pg_input_error_info('42000000000', 'integer') - - - message | detail | hint | sql_error_code -------------------------------------------------------+--------+------+---------------- - value "42000000000" is out of range for type integer | | | 22003 - - - - select message, detail from pg_input_error_info('1234.567', 'numeric(7,4)') - - - message | detail -------------------------+----------------------------------&zwsp;------------------------------------------------- - numeric field overflow | A field with precision 7, scale 4 must round to an absolute value less than 10^3. - - - - - -
- - - - - Transaction ID and Snapshot Information Functions - - - The functions shown in - provide server transaction information in an exportable form. The main - use of these functions is to determine which transactions were committed - between two snapshots. - - - - Transaction ID and Snapshot Information Functions - - - - - Function - - - Description - - - - - - - - - pg_current_xact_id - - pg_current_xact_id () - xid8 - - - Returns the current transaction's ID. It will assign a new one if the - current transaction does not have one already (because it has not - performed any database updates); see for details. If executed in a - subtransaction, this will return the top-level transaction ID; - see for details. - - - - - - - pg_current_xact_id_if_assigned - - pg_current_xact_id_if_assigned () - xid8 - - - Returns the current transaction's ID, or NULL if no - ID is assigned yet. (It's best to use this variant if the transaction - might otherwise be read-only, to avoid unnecessary consumption of an - XID.) - If executed in a subtransaction, this will return the top-level - transaction ID. - - - - - - - pg_xact_status - - pg_xact_status ( xid8 ) - text - - - Reports the commit status of a recent transaction. - The result is one of in progress, - committed, or aborted, - provided that the transaction is recent enough that the system retains - the commit status of that transaction. - If it is old enough that no references to the transaction survive in - the system and the commit status information has been discarded, the - result is NULL. - Applications might use this function, for example, to determine - whether their transaction committed or aborted after the application - and database server become disconnected while - a COMMIT is in progress. - Note that prepared transactions are reported as in - progress; applications must check pg_prepared_xacts - if they need to determine whether a transaction ID belongs to a - prepared transaction. - - - - - - - pg_current_snapshot - - pg_current_snapshot () - pg_snapshot - - - Returns a current snapshot, a data structure - showing which transaction IDs are now in-progress. - Only top-level transaction IDs are included in the snapshot; - subtransaction IDs are not shown; see - for details. - - - - - - - pg_snapshot_xip - - pg_snapshot_xip ( pg_snapshot ) - setof xid8 - - - Returns the set of in-progress transaction IDs contained in a snapshot. - - - - - - - pg_snapshot_xmax - - pg_snapshot_xmax ( pg_snapshot ) - xid8 - - - Returns the xmax of a snapshot. - - - - - - - pg_snapshot_xmin - - pg_snapshot_xmin ( pg_snapshot ) - xid8 - - - Returns the xmin of a snapshot. - - - - - - - pg_visible_in_snapshot - - pg_visible_in_snapshot ( xid8, pg_snapshot ) - boolean - - - Is the given transaction ID visible according - to this snapshot (that is, was it completed before the snapshot was - taken)? Note that this function will not give the correct answer for - a subtransaction ID (subxid); see for - details. - - - - -
- - - The internal transaction ID type xid is 32 bits wide and - wraps around every 4 billion transactions. However, - the functions shown in use a - 64-bit type xid8 that does not wrap around during the life - of an installation and can be converted to xid by casting if - required; see for details. - The data type pg_snapshot stores information about - transaction ID visibility at a particular moment in time. Its components - are described in . - pg_snapshot's textual representation is - xmin:xmax:xip_list. - For example 10:20:10,14,15 means - xmin=10, xmax=20, xip_list=10, 14, 15. - - - - Snapshot Components - - - - Name - Description - - - - - - xmin - - Lowest transaction ID that was still active. All transaction IDs - less than xmin are either committed and visible, - or rolled back and dead. - - - - - xmax - - One past the highest completed transaction ID. All transaction IDs - greater than or equal to xmax had not yet - completed as of the time of the snapshot, and thus are invisible. - - - - - xip_list - - Transactions in progress at the time of the snapshot. A transaction - ID that is xmin <= X < - xmax and not in this list was already completed at the time - of the snapshot, and thus is either visible or dead according to its - commit status. This list does not include the transaction IDs of - subtransactions (subxids). - - - - -
- - - In releases of PostgreSQL before 13 there was - no xid8 type, so variants of these functions were provided - that used bigint to represent a 64-bit XID, with a - correspondingly distinct snapshot data type txid_snapshot. - These older functions have txid in their names. They - are still supported for backward compatibility, but may be removed from a - future release. See . - - - - Deprecated Transaction ID and Snapshot Information Functions - - - - - Function - - - Description - - - - - - - - - age - - age ( xid ) - integer - - - Returns the number of transactions between the supplied - transaction id and the current transaction counter. - - - - - - - mxid_age - - mxid_age ( xid ) - integer - - - Returns the number of multixacts IDs between the supplied - multixact ID and the current multixacts counter. - - - - - - - txid_current - - txid_current () - bigint - - - See pg_current_xact_id(). - - - - - - - txid_current_if_assigned - - txid_current_if_assigned () - bigint - - - See pg_current_xact_id_if_assigned(). - - - - - - - txid_current_snapshot - - txid_current_snapshot () - txid_snapshot - - - See pg_current_snapshot(). - - - - - - - txid_snapshot_xip - - txid_snapshot_xip ( txid_snapshot ) - setof bigint - - - See pg_snapshot_xip(). - - - - - - - txid_snapshot_xmax - - txid_snapshot_xmax ( txid_snapshot ) - bigint - - - See pg_snapshot_xmax(). - - - - - - - txid_snapshot_xmin - - txid_snapshot_xmin ( txid_snapshot ) - bigint - - - See pg_snapshot_xmin(). - - - - - - - txid_visible_in_snapshot - - txid_visible_in_snapshot ( bigint, txid_snapshot ) - boolean - - - See pg_visible_in_snapshot(). - - - - - - - txid_status - - txid_status ( bigint ) - text - - - See pg_xact_status(). - - - - -
- - - - - Committed Transaction Information Functions - - - The functions shown in - provide information about when past transactions were committed. - They only provide useful data when the - configuration option is - enabled, and only for transactions that were committed after it was - enabled. Commit timestamp information is routinely removed during - vacuum. - - - - Committed Transaction Information Functions - - - - - Function - - - Description - - - - - - - - - pg_xact_commit_timestamp - - pg_xact_commit_timestamp ( xid ) - timestamp with time zone - - - Returns the commit timestamp of a transaction. - - - - - - - pg_xact_commit_timestamp_origin - - pg_xact_commit_timestamp_origin ( xid ) - record - ( timestamp timestamp with time zone, - roident oid) - - - Returns the commit timestamp and replication origin of a transaction. - - - - - - - pg_last_committed_xact - - pg_last_committed_xact () - record - ( xid xid, - timestamp timestamp with time zone, - roident oid ) - - - Returns the transaction ID, commit timestamp and replication origin - of the latest committed transaction. - - - - -
- - - - - Control Data Functions - - - The functions shown in - print information initialized during initdb, such - as the catalog version. They also show information about write-ahead - logging and checkpoint processing. This information is cluster-wide, - not specific to any one database. These functions provide most of the same - information, from the same source, as the - application. - - - - Control Data Functions - - - - - Function - - - Description - - - - - - - - - pg_control_checkpoint - - pg_control_checkpoint () - record - - - Returns information about current checkpoint state, as shown in - . - - - - - - - pg_control_system - - pg_control_system () - record - - - Returns information about current control file state, as shown in - . - - - - - - - pg_control_init - - pg_control_init () - record - - - Returns information about cluster initialization state, as shown in - . - - - - - - - pg_control_recovery - - pg_control_recovery () - record - - - Returns information about recovery state, as shown in - . - - - - -
- - - <function>pg_control_checkpoint</function> Output Columns - - - - Column Name - Data Type - - - - - - - checkpoint_lsn - pg_lsn - - - - redo_lsn - pg_lsn - - - - redo_wal_file - text - - - - timeline_id - integer - - - - prev_timeline_id - integer - - - - full_page_writes - boolean - - - - next_xid - text - - - - next_oid - oid - - - - next_multixact_id - xid - - - - next_multi_offset - xid - - - - oldest_xid - xid - - - - oldest_xid_dbid - oid - - - - oldest_active_xid - xid - - - - oldest_multi_xid - xid - - - - oldest_multi_dbid - oid - - - - oldest_commit_ts_xid - xid - - - - newest_commit_ts_xid - xid - - - - checkpoint_time - timestamp with time zone - - - - -
- - - <function>pg_control_system</function> Output Columns - - - - Column Name - Data Type - - - - - - - pg_control_version - integer - - - - catalog_version_no - integer - - - - system_identifier - bigint - - - - pg_control_last_modified - timestamp with time zone - - - - -
- - - <function>pg_control_init</function> Output Columns - - - - Column Name - Data Type - - - - - - - max_data_alignment - integer - - - - database_block_size - integer - - - - blocks_per_segment - integer - - - - wal_block_size - integer - - - - bytes_per_wal_segment - integer - - - - max_identifier_length - integer - - - - max_index_columns - integer - - - - max_toast_chunk_size - integer - - - - large_object_chunk_size - integer - - - - float8_pass_by_value - boolean - - - - data_page_checksum_version - integer - - - - -
- - - <function>pg_control_recovery</function> Output Columns - - - - Column Name - Data Type - - - - - - - min_recovery_end_lsn - pg_lsn - - - - min_recovery_end_timeline - integer - - - - backup_start_lsn - pg_lsn - - - - backup_end_lsn - pg_lsn - - - - end_of_backup_record_required - boolean - - - - -
- - - - - Version Information Functions - - - The functions shown in - print version information. - - - - Version Information Functions - - - - - Function - - - Description - - - - - - - - - version - - version () - text - - - Returns a string describing the PostgreSQL - server's version. You can also get this information from - , or for a machine-readable - version use . Software - developers should use server_version_num (available - since 8.2) or instead of - parsing the text version. - - - - - - - unicode_version - - unicode_version () - text - - - Returns a string representing the version of Unicode used by - PostgreSQL. - - - - - - icu_unicode_version - - icu_unicode_version () - text - - - Returns a string representing the version of Unicode used by ICU, if - the server was built with ICU support; otherwise returns - NULL - - - -
- - - - - WAL Summarization Information Functions - - - The functions shown in - print information about the status of WAL summarization. - See . - - - - WAL Summarization Information Functions - - - - - Function - - - Description - - - - - - - - - pg_available_wal_summaries - - pg_available_wal_summaries () - setof record - ( tli bigint, - start_lsn pg_lsn, - end_lsn pg_lsn ) - - - Returns information about the WAL summary files present in the - data directory, under pg_wal/summaries. - One row will be returned per WAL summary file. Each file summarizes - WAL on the indicated TLI within the indicated LSN range. This function - might be useful to determine whether enough WAL summaries are present - on the server to take an incremental backup based on some prior - backup whose start LSN is known. - - - - - - - pg_wal_summary_contents - - pg_wal_summary_contents ( tli bigint, start_lsn pg_lsn, end_lsn pg_lsn ) - setof record - ( relfilenode oid, - reltablespace oid, - reldatabase oid, - relforknumber smallint, - relblocknumber bigint, - is_limit_block boolean ) - - - Returns one information about the contents of a single WAL summary file - identified by TLI and starting and ending LSNs. Each row with - is_limit_block false indicates that the block - identified by the remaining output columns was modified by at least - one WAL record within the range of records summarized by this file. - Each row with is_limit_block true indicates either - that (a) the relation fork was truncated to the length given by - relblocknumber within the relevant range of WAL - records or (b) that the relation fork was created or dropped within - the relevant range of WAL records; in such cases, - relblocknumber will be zero. - - - - - - - pg_get_wal_summarizer_state - - pg_get_wal_summarizer_state () - record - ( summarized_tli bigint, - summarized_lsn pg_lsn, - pending_lsn pg_lsn, - summarizer_pid int ) - - - Returns information about the progress of the WAL summarizer. If the - WAL summarizer has never run since the instance was started, then - summarized_tli and summarized_lsn - will be 0 and 0/0 respectively; - otherwise, they will be the TLI and ending LSN of the last WAL summary - file written to disk. If the WAL summarizer is currently running, - pending_lsn will be the ending LSN of the last - record that it has consumed, which must always be greater than or - equal to summarized_lsn; if the WAL summarizer is - not running, it will be equal to summarized_lsn. - summarizer_pid is the PID of the WAL summarizer - process, if it is running, and otherwise NULL. - - - - -
- - - - +&func-info; System Administration Functions -- 2.34.1