CREATE COLLATION
CREATE COLLATION
7
SQL - Language Statements
CREATE COLLATION
define a new collation
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,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 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 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 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