1ALTER COLLATION(7) PostgreSQL 13.3 Documentation ALTER COLLATION(7)
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6 ALTER_COLLATION - change the definition of a collation
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9 ALTER COLLATION name REFRESH VERSION
10 ALTER COLLATION name RENAME TO new_name
12 ALTER COLLATION name OWNER TO { new_owner | CURRENT_USER | SESSION_USER }
13 ALTER COLLATION name SET SCHEMA new_schema
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16 ALTER COLLATION changes the definition of a collation.
17 You must own the collation to use ALTER COLLATION. To alter the owner,
19 you must also be a direct or indirect member of the new owning role,
20 and that role must have CREATE privilege on the collation's schema.
21 (These restrictions enforce that altering the owner doesn't do anything
22 you couldn't do by dropping and recreating the collation. However, a
23 superuser can alter ownership of any collation anyway.)
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26 name
27 The name (optionally schema-qualified) of an existing collation.
28 new_name
30 The new name of the collation.
31 new_owner
33 The new owner of the collation.
34 new_schema
36 The new schema for the collation.
37 REFRESH VERSION
39 Update the collation's version. See Notes below.
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42 When using collations provided by the ICU library, the ICU-specific
43 version of the collator is recorded in the system catalog when the
44 collation object is created. When the collation is used, the current
45 version is checked against the recorded version, and a warning is
46 issued when there is a mismatch, for example:
47 WARNING: collation "xx-x-icu" has version mismatch
49 DETAIL: The collation in the database was created using version 1.2.3.4, but the operating system provides version 2.3.4.5.
50 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.
51 A change in collation definitions can lead to corrupt indexes and other
53 problems because the database system relies on stored objects having a
54 certain sort order. Generally, this should be avoided, but it can
55 happen in legitimate circumstances, such as when using pg_upgrade to
56 upgrade to server binaries linked with a newer version of ICU. When
57 this happens, all objects depending on the collation should be rebuilt,
58 for example, using REINDEX. When that is done, the collation version
59 can be refreshed using the command ALTER COLLATION ... REFRESH VERSION.
60 This will update the system catalog to record the current collator
61 version and will make the warning go away. Note that this does not
62 actually check whether all affected objects have been rebuilt
63 correctly.
64 When using collations provided by libc and PostgreSQL was built with
66 the GNU C library, the C library's version is used as a collation
67 version. Since collation definitions typically change only with GNU C
68 library releases, this provides some defense against corruption, but it
69 is not completely reliable.
70 Currently, there is no version tracking for the database default
72 collation.
73 The following query can be used to identify all collations in the
75 current database that need to be refreshed and the objects that depend
76 on them:
77 SELECT pg_describe_object(refclassid, refobjid, refobjsubid) AS "Collation",
79 pg_describe_object(classid, objid, objsubid) AS "Object"
80 FROM pg_depend d JOIN pg_collation c
81 ON refclassid = 'pg_collation'::regclass AND refobjid = c.oid
82 WHERE c.collversion <> pg_collation_actual_version(c.oid)
83 ORDER BY 1, 2;
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86 To rename the collation de_DE to german:
87 ALTER COLLATION "de_DE" RENAME TO german;
89 To change the owner of the collation en_US to joe:
91 ALTER COLLATION "en_US" OWNER TO joe;
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95 There is no ALTER COLLATION statement in the SQL standard.
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98 CREATE COLLATION (CREATE_COLLATION(7)), DROP COLLATION
99 (DROP_COLLATION(7))
100PostgreSQL 13.3 2021 ALTER COLLATION(7)