51.15. pg_database

The catalog pg_database stores information about the available databases. Databases are created with the CREATE DATABASE command. Consult Chapter 21 for details about the meaning of some of the parameters.

Unlike most system catalogs, pg_database is shared across all databases of a cluster: there is only one copy of pg_database per cluster, not one per database.

Table 51.15. pg_database Columns

NameTypeReferencesDescription
oidoid Row identifier (hidden attribute; must be explicitly selected)
datnamename Database name
datdbaoidpg_authid.oidOwner of the database, usually the user who created it
encodingint4 Character encoding for this database (pg_encoding_to_char() can translate this number to the encoding name)
datcollatename LC_COLLATE for this database
datctypename LC_CTYPE for this database
datistemplatebool  If true, then this database can be cloned by any user with CREATEDB privileges; if false, then only superusers or the owner of the database can clone it.
datallowconnbool  If false then no one can connect to this database. This is used to protect the template0 database from being altered.
datconnlimitint4  Sets maximum number of concurrent connections that can be made to this database. -1 means no limit.
datlastsysoidoid  Last system OID in the database; useful particularly to pg_dump
datfrozenxidxid  All transaction IDs before this one have been replaced with a permanent (frozen) transaction ID in this database. This is used to track whether the database needs to be vacuumed in order to prevent transaction ID wraparound or to allow pg_xact to be shrunk. It is the minimum of the per-table pg_class.relfrozenxid values.
datminmxidxid  All multixact IDs before this one have been replaced with a transaction ID in this database. This is used to track whether the database needs to be vacuumed in order to prevent multixact ID wraparound or to allow pg_multixact to be shrunk. It is the minimum of the per-table pg_class.relminmxid values.
dattablespaceoidpg_tablespace.oid The default tablespace for the database. Within this database, all tables for which pg_class.reltablespace is zero will be stored in this tablespace; in particular, all the non-shared system catalogs will be there.
dataclaclitem[]  Access privileges; see GRANT and REVOKE for details