CLUSTER
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## CLUSTER

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 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, clusterdb, Section 27.4.2

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