bionic (7) CREATE_COLLATION.7.gz

NAME

       CREATE_COLLATION - define a new collation

SYNOPSIS

       CREATE COLLATION [ IF NOT EXISTS ] name (
           [ LOCALE = locale, ]
           [ LC_COLLATE = lc_collate, ]
           [ LC_CTYPE = lc_ctype, ]
           [ PROVIDER = provider, ]
           [ VERSION = version ]
       )
       CREATE COLLATION [ IF NOT EXISTS ] name FROM existing_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

       IF NOT EXISTS
           Do not throw an error if a collation with the same name already exists. A notice is issued in this
           case. Note that there is no guarantee that the existing collation is anything like the one that would
           have been created.

       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 and LC_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.

       lc_ctype
           Use the specified operating system locale for the LC_CTYPE locale category.

       provider
           Specifies the provider to use for locale services associated with this collation. Possible values
           are: icu, libc.  libc is the default. The available choices depend on the operating system and build
           options.

       version
           Specifies the version string to store with the collation. Normally, this should be omitted, which
           will cause the version to be computed from the actual version of the collation as provided by the
           operating system. This option is intended to be used by pg_upgrade for copying the version from an
           existing installation.

           See also ALTER COLLATION (ALTER_COLLATION(7)) for how to handle collation version mismatches.

       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 23.2.2.3 for more information on how to create collations.

       When using the libc collation provider, the locale must be applicable to the current database encoding.
       See CREATE DATABASE (CREATE_DATABASE(7)) for the precise rules.

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 using the ICU provider using German phone book sort order:

           CREATE COLLATION german_phonebook (provider = icu, locale = 'de-u-co-phonebk');

       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.

SEE ALSO

       ALTER COLLATION (ALTER_COLLATION(7)), DROP COLLATION (DROP_COLLATION(7))