pg_database

The catalog pg_database stores information about the available databases. Databases are created with the CREATE DATABASE command. Consult Chapter 19, Managing Databases 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.

Name	Type	References	Description
datname	name		Database name
datdba	oid	pg_authid.oid	Owner of the database, usually the user who created it
encoding	int4		Character encoding for this database
datistemplate	bool		If true then this database can be used in the TEMPLATE clause of CREATE DATABASE to create a new database as a clone of this one.
datallowconn	bool		If false then no one can connect to this database. This is used to protect the template0 database from being altered.
datconnlimit	int4		Sets maximum number of concurrent connections that can be made to this database. -1 means no limit.
datlastsysoid	oid		Last system OID in the database; useful particularly to pg_dump
datvacuumxid	xid		All rows inserted or deleted by transaction IDs before this one have been marked as known committed or known aborted in this database. This is used to determine when commit-log space can be recycled.
datfrozenxid	xid		All rows inserted by transaction IDs before this one have been relabeled with a permanent (“frozen”) transaction ID in this database. This is useful to check whether a database must be vacuumed soon to avoid transaction ID wrap-around problems.
dattablespace	oid	pg_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.
datconfig	text[]		Session defaults for run-time configuration variables
datacl	aclitem[]		Access privileges; see GRANT and REVOKE for details.