NAME¶
ALTER_INDEX - change the definition of an index
SYNOPSIS¶
ALTER INDEX [ IF EXISTS ] name RENAME TO new_name
ALTER INDEX [ IF EXISTS ] name SET TABLESPACE tablespace_name
ALTER INDEX name DEPENDS ON EXTENSION extension_name
ALTER INDEX [ IF EXISTS ] name SET ( storage_parameter = value [, ... ] )
ALTER INDEX [ IF EXISTS ] name RESET ( storage_parameter [, ... ] )
ALTER INDEX ALL IN TABLESPACE name [ OWNED BY role_name [, ... ] ]
SET TABLESPACE new_tablespace [ NOWAIT ]
DESCRIPTION¶
ALTER INDEX changes the definition of an existing index.
There are several subforms:
RENAME
The RENAME form changes the name of the index. There is
no effect on the stored data.
SET TABLESPACE
This form changes the index's tablespace to the specified
tablespace and moves the data file(s) associated with the index to the new
tablespace. To change the tablespace of an index, you must own the index and
have CREATE privilege on the new tablespace. All indexes in the current
database in a tablespace can be moved by using the ALL IN TABLESPACE form,
which will lock all indexes to be moved and then move each one. This form also
supports OWNED BY, which will only move indexes owned by the roles specified.
If the NOWAIT option is specified then the command will fail if it is unable
to acquire all of the locks required immediately. Note that system catalogs
will not be moved by this command, use ALTER DATABASE or explicit
ALTER INDEX invocations instead if desired. See also CREATE TABLESPACE
(CREATE_TABLESPACE(7)).
DEPENDS ON EXTENSION
This form marks the index as dependent on the extension,
such that if the extension is dropped, the index will automatically be dropped
as well.
SET ( storage_parameter = value [, ... ] )
This form changes one or more index-method-specific
storage parameters for the index. See CREATE INDEX (CREATE_INDEX(7))
for details on the available parameters. Note that the index contents will not
be modified immediately by this command; depending on the parameter you might
need to rebuild the index with REINDEX(7) to get the desired
effects.
RESET ( storage_parameter [, ... ] )
This form resets one or more index-method-specific
storage parameters to their defaults. As with SET, a REINDEX might be needed
to update the index entirely.
PARAMETERS¶
IF EXISTS
Do not throw an error if the index does not exist. A
notice is issued in this case.
name
The name (possibly schema-qualified) of an existing index
to alter.
new_name
The new name for the index.
tablespace_name
The tablespace to which the index will be moved.
extension_name
The name of the extension that the index is to depend
on.
storage_parameter
The name of an index-method-specific storage
parameter.
value
The new value for an index-method-specific storage
parameter. This might be a number or a word depending on the parameter.
NOTES¶
These operations are also possible using ALTER TABLE
(ALTER_TABLE(7)). ALTER INDEX is in fact just an alias for the
forms of ALTER TABLE that apply to indexes.
There was formerly an ALTER INDEX OWNER variant, but this
is now ignored (with a warning). An index cannot have an owner different
from its table's owner. Changing the table's owner automatically changes the
index as well.
Changing any part of a system catalog index is not permitted.
EXAMPLES¶
To rename an existing index:
ALTER INDEX distributors RENAME TO suppliers;
To move an index to a different tablespace:
ALTER INDEX distributors SET TABLESPACE fasttablespace;
To change an index's fill factor (assuming that the index method
supports it):
ALTER INDEX distributors SET (fillfactor = 75);
REINDEX INDEX distributors;
COMPATIBILITY¶
ALTER INDEX is a PostgreSQL extension.
SEE ALSO¶
CREATE INDEX (CREATE_INDEX(7)), REINDEX(7)