CLUSTER(7)

NAME
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 REPACK(7) 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 Section 27.4.2 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
REPACK(7), clusterdb(1), Section 27.4.2