51.15. pg_database

51.15. `pg_database`
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The catalog pg_database stores information about the available databases. Databases are created with the CREATE DATABASE command. Consult Chapter 22 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 51.15. pg_database Columns

Column Type Description
`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)
`datcollate` `name` LC_COLLATE for this database
`datctype` `name` LC_CTYPE for this database
`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.
`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.
`datlastsysoid` `oid` Last system OID in the database; useful particularly to pg_dump
`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.
`datacl` `aclitem[]` Access privileges; see Section 5.7 for details

Column Type

Description

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)

datcollate name

LC_COLLATE for this database

datctype name

LC_CTYPE for this database

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.

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.

datlastsysoid oid

Last system OID in the database; useful particularly to pg_dump

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.

datacl aclitem[]

Access privileges; see Section 5.7 for details

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