42.15. pg_database

## 42.15. `pg_database`

The catalog `pg_database` stores information about the available databases. Databases are created with the `CREATE DATABASE` command. Consult Chapter 19, Managing Databases 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 42.15. `pg_database` Columns

Name | 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
`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.
`datconnlimit` | `int4` |  | Sets maximum number of concurrent connections that can be made to this database. -1 means no limit.
`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.
`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; in particular, all the non-shared system catalogs will be there.
`datconfig` | `text[]` |  | Session defaults for run-time configuration variables
`datacl` | `aclitem[]` |  | Access privileges; see GRANT and REVOKE for details.