man > CREATE_COLLATION(7)

CREATE COLLATION(7)                PostgreSQL 16.14 Documentation                CREATE COLLATION(7)

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, ]
           [ DETERMINISTIC = boolean, ]
           [ RULES = rules, ]
           [ 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
           The locale name for this collation. See Section 24.2.2.3.1 and Section 24.2.2.3.2 for
           details.

           If provider is libc, this is a shortcut for setting LC_COLLATE and LC_CTYPE at once. If
           you specify locale, you cannot specify either of those parameters.

       lc_collate
           If provider is libc, use the specified operating system locale for the LC_COLLATE locale
           category.

       lc_ctype
           If provider is libc, 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 (if the server was built with ICU support) or libc.  libc is the
           default. See Section 24.1.4 for details.

       DETERMINISTIC
           Specifies whether the collation should use deterministic comparisons. The default is
           true. A deterministic comparison considers strings that are not byte-wise equal to be
           unequal even if they are considered logically equal by the comparison. PostgreSQL breaks
           ties using a byte-wise comparison. Comparison that is not deterministic can make the
           collation be, say, case- or accent-insensitive. For that, you need to choose an
           appropriate LOCALE setting and set the collation to not deterministic here.

           Nondeterministic collations are only supported with the ICU provider.

       rules
           Specifies additional collation rules to customize the behavior of the collation. This is
           supported for ICU only. See Section 24.2.3.4 for details.

       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
       CREATE COLLATION takes a SHARE ROW EXCLUSIVE lock, which is self-conflicting, on the
       pg_collation system catalog, so only one CREATE COLLATION command can run at a time.

       Use DROP COLLATION to remove user-defined collations.

       See Section 24.2.2.3 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 using the ICU provider, based on the root ICU locale, with custom
       rules:

           CREATE COLLATION custom (provider = icu, locale = 'und', rules = '&V << w <<< W');

       See Section 24.2.3.4 for further details and examples on the rules syntax.

       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))

PostgreSQL 16.14                                2026                             CREATE COLLATION(7)