CLUSTER

cluster a table according to an index

Synopsis

CLUSTER [ ( OPTION [, ...] ) ] [ TABLE_NAME [ USING INDEX_NAME ] ]

where OPTION can be one of:

    VERBOSE [ BOOLEAN ]

Description

The CLUSTER command is equivalent to sql-repack with a USING INDEX clause. See there for more details.

Parameters

table_name

The name (possibly schema-qualified) of a table.

index_name

The name of an index.

VERBOSE

Prints a progress report as each table is clustered at INFO level.

boolean

Specifies whether the selected option should be turned on or off. You can write TRUE, ON, or 1 to enable the option, and FALSE, OFF, or 0 to disable it. The boolean value can also be omitted, in which case TRUE is assumed.

Notes

To cluster a table, one must have the MAINTAIN privilege on the table.

While CLUSTER is running, the search_path is temporarily changed to pg_catalog, pg_temp.

Because CLUSTER remembers which indexes are clustered, one can cluster the tables one wants clustered manually the first time, then set up a periodic maintenance script that executes CLUSTER without any parameters, so that the desired tables are periodically reclustered.

Each backend running CLUSTER will report its progress in the pg_stat_progress_cluster view. See CLUSTER Progress Reporting for details.

Clustering a partitioned table clusters each of its partitions using the partition of the specified partitioned index. When clustering a partitioned table, the index may not be omitted. CLUSTER on a partitioned table cannot be executed inside a transaction block.

Examples

Cluster the table employees on the basis of its index employees_ind:

CLUSTER employees USING employees_ind;

Cluster the employees table using the same index that was used before:

CLUSTER employees;

Cluster all tables in the database that have previously been clustered:

CLUSTER;

Compatibility

There is no CLUSTER statement in the SQL standard.

The following syntax was used before PostgreSQL 17 and is still supported:

CLUSTER [ VERBOSE ] [ TABLE_NAME [ USING INDEX_NAME ] ]

The following syntax was used before PostgreSQL 8.3 and is still supported:

CLUSTER INDEX_NAME ON TABLE_NAME

See Also

sql-repack, app-clusterdb, CLUSTER Progress Reporting