CREATE COLLATION
CREATE COLLATION — define a new collation
Synopsis
CREATE COLLATIONname
( [ LOCALE =locale
, ] [ LC_COLLATE =lc_collate
, ] [ LC_CTYPE =lc_ctype
] ) CREATE COLLATIONname
FROMexisting_collation
Description
CREATE COLLATION
defines a new collation using the specified operating system locale settings, or by copying an existing collation.
To be able to create a collation, you must have CREATE
privilege on the destination schema.
Parameters
name
The name of the collation. The collation name can be schema-qualified. If it is not, the collation is defined in the current schema. The collation name must be unique within that schema. (The system catalogs can contain collations with the same name for other encodings, but these are ignored if the database encoding does not match.)
locale
This is a shortcut for setting
LC_COLLATE
andLC_CTYPE
at once. If you specify this, you cannot specify either of those parameters.lc_collate
Use the specified operating system locale for the
LC_COLLATE
locale category. The locale must be applicable to the current database encoding. (See CREATE DATABASE for the precise rules.)lc_ctype
Use the specified operating system locale for the
LC_CTYPE
locale category. The locale must be applicable to the current database encoding. (See CREATE DATABASE for the precise rules.)existing_collation
The name of an existing collation to copy. The new collation will have the same properties as the existing one, but it will be an independent object.
Notes
Use DROP COLLATION
to remove user-defined collations.
See Section 22.2 for more information about collation support in PostgreSQL.
Examples
To create a collation from the operating system locale fr_FR.utf8
(assuming the current database encoding is UTF8
):
CREATE COLLATION french (LOCALE = 'fr_FR.utf8');
To create a collation from an existing collation:
CREATE COLLATION german FROM "de_DE";
This can be convenient to be able to use operating-system-independent collation names in applications.
Compatibility
There is a CREATE COLLATION
statement in the SQL standard, but it is limited to copying an existing collation. The syntax to create a new collation is a PostgreSQL extension.