System Catalogs Definitions - pg_database - 《Greenplum Database v6.24 Documentation》

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