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ALTER INDEX

Name

ALTER INDEX -- change the definition of an index

Synopsis

ALTER INDEX name RENAME TO new_name
ALTER INDEX name SET TABLESPACE tablespace_name
ALTER INDEX name SET ( storage_parameter = value [, ... ] )
ALTER INDEX name RESET ( storage_parameter [, ... ] )

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. See also CREATE TABLESPACE.

SET ( storage_parameter = value [, ... ] )

This form changes one or more index-method-specific storage parameters for the index. See CREATE INDEX 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 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

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.

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 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.

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