ALTER COLLATION(7) PostgreSQL 10.1 Documentation ALTER COLLATION(7)NAMEALTER_COLLATION - change the definition of a collation
SYNOPSIS
ALTER COLLATION name REFRESH VERSION
ALTER COLLATION name RENAME TO new_name
ALTER COLLATION name OWNER TO { new_owner | CURRENT_USER | SESSION_USER }
ALTER COLLATION name SET SCHEMA new_schema
DESCRIPTION
ALTER COLLATION changes the definition of a collation.
You must own the collation to use ALTER COLLATION. To alter the owner,
you must also be a direct or indirect member of the new owning role,
and that role must have CREATE privilege on the collation's schema.
(These restrictions enforce that altering the owner doesn't do anything
you couldn't do by dropping and recreating the collation. However, a
superuser can alter ownership of any collation anyway.)
PARAMETERS
name
The name (optionally schema-qualified) of an existing collation.
new_name
The new name of the collation.
new_owner
The new owner of the collation.
new_schema
The new schema for the collation.
REFRESH VERSION
Update the collation's version. See NOTES below.
NOTES
When using collations provided by the ICU library, the ICU-specific
version of the collator is recorded in the system catalog when the
collation object is created. When the collation is used, the current
version is checked against the recorded version, and a warning is
issued when there is a mismatch, for example:
WARNING: collation "xx-x-icu" has version mismatch
DETAIL: The collation in the database was created using version 1.2.3.4, but the operating system provides version 2.3.4.5.
HINT: Rebuild all objects affected by this collation and run ALTER COLLATION pg_catalog."xx-x-icu" REFRESH VERSION, or build PostgreSQL with the right library version.
A change in collation definitions can lead to corrupt indexes and other
problems because the database system relies on stored objects having a
certain sort order. Generally, this should be avoided, but it can
happen in legitimate circumstances, such as when using pg_upgrade to
upgrade to server binaries linked with a newer version of ICU. When
this happens, all objects depending on the collation should be rebuilt,
for example, using REINDEX. When that is done, the collation version
can be refreshed using the command ALTER COLLATION ... REFRESH VERSION.
This will update the system catalog to record the current collator
version and will make the warning go away. Note that this does not
actually check whether all affected objects have been rebuilt
correctly.
The following query can be used to identify all collations in the
current database that need to be refreshed and the objects that depend
on them:
SELECT pg_describe_object(refclassid, refobjid, refobjsubid) AS "Collation",
pg_describe_object(classid, objid, objsubid) AS "Object"
FROM pg_depend d JOIN pg_collation c
ON refclassid = 'pg_collation'::regclass AND refobjid = c.oid
WHERE c.collversion <> pg_collation_actual_version(c.oid)
ORDER BY 1, 2;
EXAMPLES
To rename the collation de_DE to german:
ALTER COLLATION "de_DE" RENAME TO german;
To change the owner of the collation en_US to joe:
ALTER COLLATION "en_US" OWNER TO joe;
COMPATIBILITY
There is no ALTER COLLATION statement in the SQL standard.
SEE ALSO
CREATE COLLATION (CREATE_COLLATION(7)), DROP COLLATION
(DROP_COLLATION(7))
PostgreSQL 10.1 2017 ALTER COLLATION(7)
