ALTER INDEX v16
Name
ALTER INDEX — Modify an existing index.
Synopsis
EDB Postgres Advanced Server supports three variations of the ALTER INDEX command compatible with Oracle databases. Use the first variation to rename an index:
ALTER INDEX <name> RENAME TO <new_name>
Use the second variation of the ALTER INDEX command to rebuild an index:
ALTER INDEX <name> REBUILD
Use the third variation of the ALTER INDEX command to set the PARALLEL or NOPARALLEL clause:
ALTER INDEX <name> { NOPARALLEL | PARALLEL [ <integer> ] }
Description
ALTER INDEX changes the definition of an existing index. The RENAME clause changes the name of the index. The REBUILD clause reconstructs an index, replacing the old copy of the index with an updated version based on the index's table.
The REBUILD clause invokes the PostgreSQL REINDEX command. For more information about using the REBUILD clause, see the PostgreSQL core documentation.
The PARALLEL clause sets the degree of parallelism for an index that can be used to parallelize rebuilding an index.
The NOPARALLEL clause resets parallelism to use default values. reloptions shows the parallel_workers parameter as 0.
ALTER INDEX has no effect on stored data.
Parameters
name
The name (possibly schema-qualified) of an existing index.
new_name
New name for the index.
PARALLEL
Include the PARALLEL clause to specify a degree of parallelism. Set the parallel_workers parameter equal to the degree of parallelism for rebuilding an index. If you specify PARALLEL but don't provide a degree of parallelism, the default parallelism is used.
NOPARALLEL
Specify NOPARALLEL to reset parallelism to default values.
integer
The integer indicates the degree of parallelism, that is, the number of parallel_workers used when rebuilding an index.
Examples
To change the name of an index from name_idx to empname_idx:
ALTER INDEX name_idx RENAME TO empname_idx;
To rebuild an index named empname_idx:
ALTER INDEX empname_idx REBUILD;
This example sets the degree of parallelism on an empname_idx index to 7:
ALTER INDEX empname_idx PARALLEL 7;