The pg_cursors view lists the cursors that are currently available. Cursors can be defined in several ways: via the DECLARE statement in SQL via the Bind message in the frontend/backend protocol, as described in Section 51.2.3 via the Server Programming Interface (SPI), as described in Section 45.1 The pg_cursors view displays cursors created by any of these means. Cursors only exist for the duration of the transaction that defines them, unless they have been declared WITH HOLD. Therefo

The catalog pg_conversion describes encoding conversion procedures. See CREATE CONVERSION for more information. Table 50-14. pg_conversion Columns Name Type References Description oid oid Row identifier (hidden attribute; must be explicitly selected) conname name Conversion name (unique within a namespace) connamespace oid pg_namespace.oid The OID of the namespace that contains this conversion conowner oid pg_authid.oid Owner of the conversion conforencoding int4 Source encoding ID cont

The catalog pg_constraint stores check, primary key, unique, foreign key, and exclusion constraints on tables. (Column constraints are not treated specially. Every column constraint is equivalent to some table constraint.) Not-null constraints are represented in the pg_attribute catalog, not here. User-defined constraint triggers (created with CREATE CONSTRAINT TRIGGER) also give rise to an entry in this table. Check constraints on domains are stored here, too. Table 50-13. pg_constraint Colu

The view pg_config describes the compile-time configuration parameters of the currently installed version of PostgreSQL. It is intended, for example, to be used by software packages that want to interface to PostgreSQL to facilitate finding the required header files and libraries. It provides the same basic information as the pg_config PostgreSQL client application. By default, the pg_config view can be read only by superusers. Table 50-61. pg_config Columns Name Type Description name text Th

The catalog pg_collation describes the available collations, which are essentially mappings from an SQL name to operating system locale categories. See Section 23.2 for more information. Table 50-12. pg_collation Columns Name Type References Description oid oid Row identifier (hidden attribute; must be explicitly selected) collname name Collation name (unique per namespace and encoding) collnamespace oid pg_namespace.oid The OID of the namespace that contains this collation collowner oid

The catalog pg_class catalogs tables and most everything else that has columns or is otherwise similar to a table. This includes indexes (but see also pg_index), sequences, views, materialized views, composite types, and TOAST tables; see relkind. Below, when we mean all of these kinds of objects we speak of "relations". Not all columns are meaningful for all relation types. Table 50-11. pg_class Columns Name Type References Description oid oid Row identifier (hidden attribute; must be expl

The catalog pg_cast stores data type conversion paths, both built-in and user-defined. It should be noted that pg_cast does not represent every type conversion that the system knows how to perform; only those that cannot be deduced from some generic rule. For example, casting between a domain and its base type is not explicitly represented in pg_cast. Another important exception is that "automatic I/O conversion casts", those performed using a data type's own I/O functions to convert to or from

The pg_available_extension_versions view lists the specific extension versions that are available for installation. See also the pg_extension catalog, which shows the extensions currently installed. Table 50-60. pg_available_extension_versions Columns Name Type Description name name Extension name version text Version name installed bool True if this version of this extension is currently installed superuser bool True if only superusers are allowed to install this extension relocatable bool T

The pg_available_extensions view lists the extensions that are available for installation. See also the pg_extension catalog, which shows the extensions currently installed. Table 50-59. pg_available_extensions Columns Name Type Description name name Extension name default_version text Name of default version, or NULL if none is specified installed_version text Currently installed version of the extension, or NULL if not installed comment text Comment string from the extension's control file

The catalog pg_auth_members shows the membership relations between roles. Any non-circular set of relationships is allowed. Because user identities are cluster-wide, pg_auth_members is shared across all databases of a cluster: there is only one copy of pg_auth_members per cluster, not one per database. Table 50-9. pg_auth_members Columns Name Type References Description roleid oid pg_authid.oid ID of a role that has a member member oid pg_authid.oid ID of a role that is a member of roleid gr