Oracle in a Nutshell

Name

CREATE/ALTER/DROP CLUSTER

Synopsis

CREATE Syntax:

CREATE CLUSTER [schema.]cluster_name 
(column  datatype[, column  datatype ...])
[Physical_Attributes_Clause]
[SIZE integer [K | M]]
[TABLESPACE tablespace_name]
[Storage_Clause]
[INDEX]
[[SINGLE TABLE] HASHKEYS integer HASH IS expr]
[{PARALLEL [integer] | NOPARALLEL}]
[CACHE | NOCACHE]

ALTER Syntax:

ALTER CLUSTER [schema.]clustername
[SIZE integer [K | M]]
[Physical_Attributes_Clause]
[Storage_Clause]
[PARALLEL [integer] | NOPARALLEL]
[ALLOCATE EXTENT 
  (EXTSIZE integer [K | M] [DATAFILE 'filename'] [INSTANCE integer])]

DROP Syntax:

DROP CLUSTER [schema.]clustername
[INCLUDING TABLES]
[CASCADE CONSTRAINTS]

Creates, modifies, or drops a cluster, which is a schema object containing one or more tables with one or more columns in common. Clustering can improve database performance and efficiency. With clustering, common columns are stored only once, and the data from all tables is normally stored contiguously.

Keywords

cluster_name

Name of the cluster.

datatype

Datatype of the column.

TABLESPACE

Specifies the name of the tablespace where this cluster will be stored. If omitted, the default tablespace for the schema owner will be used.

INDEX

Specifies that an indexed cluster be created. This keyword is not valid for a hash cluster.

SINGLE TABLE

Specifies that this cluster is a special type containing only one table. New with Oracle8i.

HASHKEYS integer

Specifies that a hash cluster be created with integer hash keys.

HASH IS expr

Specifies an expression ...