Provides the backend server with clustering information about a table.
CLUSTER indexname ON tablename
indexname
The name of the index to use in clustering.
tablename
The name of the table you wish to cluster.
CLUSTER
The message returned when a table is successfully clustered.
ERROR: CLUSTER: "
indexname
" is not an index for table
"
tablename
"
The error returned if you attempt to cluster an index indexname
which is not placed on the specified table
(tablename
).
ERROR: Index "
indexname
" does not exist
The error returned if the specified index (indexname
) cannot be found in the connected database.
ERROR: Relation "
tablename
" does not exist
The error returned if the specified table (tablename
) cannot be found in the connected database.
ERROR: Relation "
child_table
" inherits from "
tablename
"
The error returned if the specified table (tablename
) is inherited by another table (child_table
).
Use the CLUSTER
command to cluster a table on a specific index. The
table (identified by the tablename
parameter) must
already, exist and the index (identified by the indexname
parameter) must exist, and be placed on the table.
During clustering, a table is reordered for performance in an arrangement based on the specified index. A cluster is a one-time operation upon a table; to recluster a table, you must execute the command again.
When a cluster is created, the rows of the table are actually copied to a temporary table according to an order derived from the specified index. That temporary table is then renamed to the original table name. Because of this, all permissions and other indices are lost when clustering is performed.
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