SYSTEM CATALOG · System catalog

pg_collation

PostgreSQL documentation ↗Source definition ↗

The catalog pg_collation describes the available collations, which are essentially mappings from an SQL name to operating system locale categories. See Section 23.2 for more information.

First seen PG 9.1Last seen PG 19Columns 12

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_collation

COLUMN	TYPE	DESCRIPTION
`oid`	`oid`NOT NULL	Row identifier
`collname`	`name`NOT NULL	Collation name (unique per namespace and encoding)
`collnamespace`	`oid`NOT NULL	The OID of the namespace that contains this collationReferences:`pg_namespace.oid`
`collowner`	`oid`NOT NULL	Owner of the collationReferences:`pg_authid.oid`
`collprovider`	`"char"`NOT NULLDocumented as:`char`	Provider of the collation: d = database default, b = builtin, c = libc, i = icu
`collisdeterministic`	`boolean`NOT NULLDocumented as:`bool`	Is the collation deterministic?
`collencoding`	`integer`NOT NULLDocumented as:`int4`	Encoding in which the collation is applicable, or -1 if it works for any encoding
`collcollate`	`text`	LC_COLLATE for this collation object. If the provider is not libc, collcollate is NULL and colllocale is used instead.
`collctype`	`text`	LC_CTYPE for this collation object. If the provider is not libc, collctype is NULL and colllocale is used instead.
`colllocale`	`text`	Collation provider locale name for this collation object. If the provider is libc, colllocale is NULL; collcollate and collctype are used instead.
`collicurules`	`text`	ICU collation rules for this collation object
`collversion`	`text`	Provider-specific version of the collation. This is recorded when the collation is created and then checked when it is used, to detect changes in the collation definition that could lead to data corruption.

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`	–
`collname`	–
`collnamespace`	–
`collowner`	–
`collencoding`	–
`collcollate`	–
`collctype`	–
`collprovider`	–	–	–	–	–	–	–
`collversion`	–	–	–	–	–	–	–
`collisdeterministic`	–	–	–	–	–	–	–	–	–
`colliculocale`	–	–	–	–	–	–	–	–	–	–	–	–			−	–	–
`collicurules`	–	–	–	–	–	–	–	–	–	–	–	–	–
`colllocale`	–	–	–	–	–	–	–	–	–	–	–	–	–	–

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 17 ← 16

+ colllocale− colliculocale3 column description updatesCatalog description updated

PostgreSQL 16 ← 15

+ collicurules

PostgreSQL 15 ← 14

+ colliculocale~ collcollate: name → text~ collctype: name → text~ collcollate: not_null: true → false~ collctype: not_null: true → false

PostgreSQL 14 ← 13

Catalog description updated

PostgreSQL 12 ← 11

+ collisdeterministic~ oid: implicit → ordinary1 column description updates

PostgreSQL 10 ← 9.6

+ collprovider+ collversion

PostgreSQL 9.6 ← 9.5

Catalog description updated

PostgreSQL 9.3 ← 9.2

1 column description updates

PostgreSQL 9.1 ← 9.0Catalog added

+ oid+ collname+ collnamespace+ collowner+ collencoding+ collcollate+ collctype

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FROMTOInclude description updates

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