PostgreSQL

Returns the name of the current database. (Databases are called “[.quote]#catalogs”# in the SQL standard, so current_catalog is the standard’s spelling.)

Returns the text of the currently executing query, as submitted by the client (which might contain more than one statement).

This is equivalent to current_user.

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.

Returns an array of the names of all schemas presently in the effective search path, in their priority order. (Items in the current search_path 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.

Returns the user name of the current execution context.

Returns the IP address of the current client, or NULL if the current connection is via a Unix-domain socket.

Returns the IP port number of the current client, or NULL if the current connection is via a Unix-domain socket.

Returns the IP address on which the server accepted the current connection, or NULL if the current connection is via a Unix-domain socket.

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.

Returns the process ID of the server process attached to the current session.

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.

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.

Returns the path name of the log file currently in use by the logging collector. The path includes the log_directory 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. NULL is returned if no log file has any of these formats. To request information about a specific log file format, supply either csvlog or stderr as the value of the optional parameter. The result is NULL if the log format requested is not configured in log_destination. The result reflects the contents of the current_logfiles file.

Returns the OID of the current session’s temporary schema, or zero if it has none (because it has not created any temporary tables).

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.)

Returns true if a JIT compiler extension is available (see Chapter 32) and the jit configuration parameter is set to on.

Returns the set of names of asynchronous notification channels that the current session is listening to.

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 LISTEN and NOTIFY for more information.

Returns the time when the server started.

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 Section 13.2.3 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.

Returns the current nesting level of PostgreSQL triggers (0 if not called, directly or indirectly, from inside a trigger).

Returns the session user’s name.

This is equivalent to current_user.

Returns a string describing the PostgreSQL server’s version. You can also get this information from server_version, or for a machine-readable version use server_version_num. Software developers should use server_version_num (available since 8.2) or PQserverVersion instead of parsing the text version.

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.

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.

Does user have privilege for database? Allowable privilege types are CREATE, CONNECT, TEMPORARY, and TEMP (which is equivalent to TEMPORARY).

Does user have privilege for foreign-data wrapper? The only allowable privilege type is USAGE.

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 Section 8.19). An example is:

Does user have privilege for language? The only allowable privilege type is USAGE.

Does user have privilege for schema? Allowable privilege types are CREATE and USAGE.

Does user have privilege for sequence? Allowable privilege types are USAGE, SELECT, and UPDATE.

Does user have privilege for foreign server? The only allowable privilege type is USAGE.

Does user have privilege for table? Allowable privilege types are SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, and TRIGGER.

Does user have privilege for tablespace? The only allowable privilege type is CREATE.

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 Section 8.19).

Does user have privilege for role? Allowable privilege types are MEMBER and USAGE. MEMBER denotes direct or indirect membership in the role (that is, the right to do SET ROLE), while USAGE denotes whether the privileges of the role are immediately available without doing SET ROLE. 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.

Is row-level security active for the specified table in the context of the current user and current environment?

Are aclitem`s 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

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

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 Section 5.7.) 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, 't' for TABLESPACE, 'F' for FOREIGN DATA WRAPPER, 'S' for FOREIGN SERVER, or 'T' for TYPE or DOMAIN.

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. Note that each privilege is broken out as a separate row, so only one keyword appears in the `privilege_type` column.

Constructs an aclitem with the given properties.

Is collation visible in search path?

Is conversion visible in search path?

Is function visible in search path? (This also works for procedures and aggregates.)

Is operator class visible in search path?

Is operator visible in search path?

Is operator family visible in search path?

Is statistics object visible in search path?

Is table visible in search path? (This works for all types of relations, including views, materialized views, indexes, sequences and foreign tables.)

Is text search configuration visible in search path?

Is text search dictionary visible in search path?

Is text search parser visible in search path?

Is text search template visible in search path?

Is type (or domain) visible in search path?

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.

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.

Reconstructs the creating command for a constraint. (This is a decompiled reconstruction, not the original text of the command.)

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.

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.

Reconstructs the argument list of a function or procedure, in the form it would need to appear in within CREATE FUNCTION (including default values).

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.

Reconstructs the RETURNS clause of a function, in the form it would need to appear in within CREATE FUNCTION. Returns NULL for a procedure.

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.

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 “[.quote]#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.

Reconstructs the creating command for a rule. (This is a decompiled reconstruction, not the original text of the command.)

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 Section 9.17).

A typical use is in reading the current value of the sequence for an identity or serial column, for example:

Reconstructs the creating command for an extended statistics object. (This is a decompiled reconstruction, not the original text of the command.)

Reconstructs the creating command for a trigger. (This is a decompiled reconstruction, not the original text of the command.)

Returns a role’s name given its OID.

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.)

Tests whether an index column has the named property. Common index column properties are listed in Table 9.71. (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.

Tests whether an index has the named property. Common index properties are listed in Table 9.72. (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.

Tests whether an index access method has the named property. Access method properties are listed in Table 9.73. 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.

Returns the set of storage options represented by a value from pg_class.reloptions or pg_attribute.attoptions.

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.

Returns the file system path that this tablespace is located in.

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 Section 8.19); this means that it is the same as an OID for comparison purposes but displays as a type name.

For example:

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.

For example:

Translates a textual relation name to its OID. A similar result is obtained by casting the string to type regclass (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found. Also unlike the cast, this does not accept a numeric OID as input.

Translates a textual collation name to its OID. A similar result is obtained by casting the string to type regcollation (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found. Also unlike the cast, this does not accept a numeric OID as input.

Translates a textual schema name to its OID. A similar result is obtained by casting the string to type regnamespace (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found. Also unlike the cast, this does not accept a numeric OID as input.

Translates a textual operator name to its OID. A similar result is obtained by casting the string to type regoper (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found or is ambiguous. Also unlike the cast, this does not accept a numeric OID as input.

Translates a textual operator name (with parameter types) to its OID. A similar result is obtained by casting the string to type regoperator (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found. Also unlike the cast, this does not accept a numeric OID as input.

Translates a textual function or procedure name to its OID. A similar result is obtained by casting the string to type regproc (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found or is ambiguous. Also unlike the cast, this does not accept a numeric OID as input.

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 Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found. Also unlike the cast, this does not accept a numeric OID as input.

Translates a textual role name to its OID. A similar result is obtained by casting the string to type regrole (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found. Also unlike the cast, this does not accept a numeric OID as input.

Translates a textual type name to its OID. A similar result is obtained by casting the string to type regtype (see Section 8.19); however, this function will return NULL rather than throwing an error if the name is not found. Also unlike the cast, this does not accept a numeric OID as input.

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.

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.

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.

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.

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.)

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.

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.

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).

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.)

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.

Returns a current snapshot, a data structure showing which transaction IDs are now in-progress.

Returns the set of in-progress transaction IDs contained in a snapshot.

Returns the xmax of a snapshot.

Returns the xmin of a snapshot.

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.

See pg_current_xact_id().

See pg_current_xact_id_if_assigned().

See pg_current_snapshot().

See pg_snapshot_xip().

See pg_snapshot_xmax().

See pg_snapshot_xmin().

See pg_visible_in_snapshot().

See pg_xact_status().

Returns the commit timestamp of a transaction.

Returns the commit timestamp and replication origin of a transaction.

Returns the transaction ID, commit timestamp and replication origin of the latest committed transaction.

Returns information about current checkpoint state, as shown in Table 9.81.

Returns information about current control file state, as shown in Table 9.82.

Returns information about cluster initialization state, as shown in Table 9.83.

Returns information about recovery state, as shown in Table 9.84.