ALTER INDEX changes the definition of an existing index. There are several subforms:
The RENAME form changes the name of the index. There is no effect on the stored data.
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.
The name (possibly schema-qualified) of an existing index to alter.
New name for the index.
The tablespace to which the index will be moved.
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.
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;