SYSTEM CATALOG · System catalog

pg_database

PostgreSQL documentation ↗Source definition ↗

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.

First seen PG 9.0Last seen PG 19Columns 18

9.0 9.1 9.2 9.3 9.4 9.5 9.6 10 11 12 13 14 15 16 17 18 19^β3

Checked column by column against a PostgreSQL 18.6 instance · Raw measurement record ↗

Columns PostgreSQL 18

pg_database

COLUMN	TYPE	DESCRIPTION
`oid`	`oid`NOT NULL	Row identifier
`datname`	`name`NOT NULL	Database name
`datdba`	`oid`NOT NULL	Owner of the database, usually the user who created itReferences:`pg_authid.oid`
`encoding`	`integer`NOT NULLDocumented as:`int4`	Character encoding for this database (pg_encoding_to_char() can translate this number to the encoding name)
`datlocprovider`	`"char"`NOT NULLDocumented as:`char`	Locale provider for this database: b = builtin, c = libc, i = icu
`datistemplate`	`boolean`NOT NULLDocumented as:`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`	`boolean`NOT NULLDocumented as:`bool`	If false then no one can connect to this database. This is used to protect the template0 database from being altered.
`dathasloginevt`	`boolean`NOT NULLDocumented as:`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`	`integer`NOT NULLDocumented as:`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`NOT NULL	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`NOT NULL	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`NOT NULL	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.References:`pg_tablespace.oid`
`datcollate`	`text`NOT NULL	LC_COLLATE for this database
`datctype`	`text`NOT NULL	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

Columns marked "implicit" are not included in SELECT *; some early statistics views are completed from same-version source, and the extra provenance is shown in the column description.

Common system columns 6

System attributes PostgreSQL provides, normally not expanded by SELECT *. Kept separately so they are not mixed in with ordinary columns.

Columns	Type	attnum
`tableoid`	`oid`	-6
`cmax`	`cid`	-5
`xmax`	`xid`	-4
`cmin`	`cid`	-3
`xmin`	`xid`	-2
`ctid`	`tid`	-1

Column evolution matrix

Hover a cell for the column type

PresentAdded / type or attribute changeRemoved

COLUMN	9.0	9.1	9.2	9.3	9.4	9.5	9.6	10	11	12	13	14	15	16	17	18	19
`oid`
`datname`
`datdba`
`encoding`
`datcollate`
`datctype`
`datistemplate`
`datallowconn`
`datconnlimit`
`datlastsysoid`													−	–	–	–	–
`datfrozenxid`
`dattablespace`
`datacl`
`datminmxid`	–	–	–
`datlocprovider`	–	–	–	–	–	–	–	–	–	–	–	–
`daticulocale`	–	–	–	–	–	–	–	–	–	–	–	–			−	–	–
`datcollversion`	–	–	–	–	–	–	–	–	–	–	–	–
`daticurules`	–	–	–	–	–	–	–	–	–	–	–	–	–
`dathasloginevt`	–	–	–	–	–	–	–	–	–	–	–	–	–	–
`datlocale`	–	–	–	–	–	–	–	–	–	–	–	–	–	–

9.0 is the coverage baseline; a column already present in the baseline is not marked as added. The matrix aligns columns by name, so a rename appears as the old column removed and a new column added.

Evolution timeline

Changes between adjacent majors

PostgreSQL 19 ← 18

2 column description updates

PostgreSQL 17 ← 16

+ dathasloginevt+ datlocale− daticulocale2 column description updatesCatalog description updated

PostgreSQL 16 ← 15

+ daticurules

PostgreSQL 15 ← 14

+ datlocprovider+ daticulocale+ datcollversion− datlastsysoid~ datcollate: name → text~ datctype: name → text↕ Column order changed

PostgreSQL 14 ← 13

Catalog description updated

PostgreSQL 12 ← 11

~ oid: implicit → ordinary2 column description updates

PostgreSQL 11 ← 10

1 column description updates

PostgreSQL 10 ← 9.6

1 column description updates

PostgreSQL 9.6 ← 9.5

Catalog description updated

PostgreSQL 9.4 ← 9.3

1 column description updates

PostgreSQL 9.3 ← 9.2

+ datminmxid1 column description updates

Compare any two versions

FROMTOInclude description updates

Pick two versions to see added, removed, and retyped columns. The interactive comparison needs JavaScript; the evolution timeline reads fine without it.