The pg_database system catalog table stores information about the available databases. Databases are created with the CREATE DATABASE SQL command. Unlike most system catalogs, pg_database is shared across all databases in the system. There is only one copy of pg_database per system, not one per database.
| column | 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. pg_encoding_to_char() can translate this number to the encoding name. | |
datcollate | name | LC_COLLATE for this database. | |
datctype | name | LC_CTYPE for this database. | |
datistemplate | boolean | 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 | boolean | If false then no one can connect to this database. This is used to protect the template0 database from being altered. | |
datconnlimit | int4 | Sets the maximum number of concurrent connections that can be made to this database. -1 means no limit. | |
datlastsysoid | oid | Last system OID in the database. | |
datfrozenxid | xid | All transaction IDs (XIDs) 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_clog to be shrunk. It is the minimum of the per-table pg_class.relfrozenxid values. | |
datminmxid | xid | A Multixact ID is used to support row locking by multiple transactions. 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 | 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. All non-shared system catalogs will also be there. |
datacl | aclitem[] | Database access privileges as given by GRANT and REVOKE. |
Parent topic: System Catalogs Definitions