pg_database — PostgreSQL system catalog

The PostgreSQL pg_database system catalog: full column reference (names, types, descriptions), catalog relationships and version support.

The Sev-1 Admin
The Sev-1 Admin  ·  3 min read

Summary

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

(Description quoted from the official PostgreSQL documentation.)

Columns

The pg_database system catalog exposes the following columns (names, types and descriptions are taken verbatim from the PostgreSQL documentation):

  • oid oid
    Row identifier
  • datname name
    Database name
  • datdba oid references pg_authid.oid
    Owner of the database, usually the user who created it
  • encoding int4
    Character encoding for this database (pg_encoding_to_char() can translate this number to the encoding name)
  • datlocprovider char
    Locale provider for this database: b = builtin, c = libc, i = icu
  • datistemplate bool
    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.
  • datallowconn bool
    If false then no one can connect to this database. This is used to protect the template0 database from being altered.
  • dathasloginevt bool
    Indicates that there are login event triggers defined for this database. This flag is used to avoid extra lookups on the pg_event_trigger table during each backend startup. This flag is used internally by PostgreSQL and should not be manually altered or read for monitoring purposes.
  • datconnlimit int4
    Sets maximum number of concurrent connections that can be made to this database. -1 means no limit, -2 indicates the database is invalid.
  • datfrozenxid xid
    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.
  • datminmxid xid
    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.
  • dattablespace oid references 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.
  • datcollate text
    LC_COLLATE for this database (ignored unless datlocprovider is c)
  • datctype text
    LC_CTYPE for this database
  • datlocale text
    Collation provider locale name for this database. If the provider is libc, datlocale is NULL; datcollate and datctype are used instead.
  • daticurules text
    ICU collation rules for this database
  • datcollversion text
    Provider-specific version of the collation. This is recorded when the database is created and then checked when it is used, to detect changes in the collation definition that could lead to data corruption.
  • datacl aclitem[]
    Access privileges; see ddl_priv for details

Related catalogs

This object references the following other system catalogs:

Version applicability

Present in PostgreSQL 17, 18, 19 (verified against each release’s documentation). This is a long-standing system object that also exists in earlier PostgreSQL releases.

Related & references

Reference: PostgreSQL documentation — pg_database.