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)
`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
`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 Section 5.8 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)

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

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 Section 5.8 for details

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