The pg_database catalog stores information about the available databases. Databases are created with the CREATE DATABASE command. Consult the Administrator's Guide 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 3-6. pg_database Columns
|datdba||int4||pg_shadow.usesysid||Owner of the database, initially who created it|
|encoding||int4||Character/multibyte encoding for this database|
|datistemplate||bool||If true then this database can be used in the "TEMPLATE" clause of CREATE DATABASE to create the 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.|
|datlastsysoid||oid||Last system OID in the database; useful particularly to pg_dump|
|datvacuumxid||xid||All tuples 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 tuples 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 wraparound problems.|
|datpath||text||If the database is stored at an alternative location then this records the location. It's either an environment variable name or an absolute path, depending how it was entered.|