The catalog pg_database stores information about the available databases. Databases are created with the CREATE DATABASE command. Consult Chapter 18 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 43-12. pg_database Columns
|datdba||int4||pg_shadow.usesysid||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.|
|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.|
|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.|
|datconfig||text||Session defaults for run-time configuration variables|