CREATE OPTICAL CLUSTER (+, DB-Access, ESQL/C)

>>-CREATE OPTICAL CLUSTER--+-------+--cluster_name-------------->
                           '-owner-'
 
>--| FOR Clause |--| ON Clause |--+------------------------+---><
                                  '-| CLUSTERSIZE Clause |-'
 
FOR Clause:
 
|--FOR--| Table Name see Database Object Name in SQLS |--------->
 
      .-'-----------.
      V             |
>--(----column_name-+--)----------------------------------------|
 
ON Clause:
 
          .-'-----------------------.
          V                         |
|--ON--(----cluster-key column_name-+--)------------------------|
 
CLUSTERSIZE Clause:
 
                .-500---------.
|--CLUSTERSIZE--+-------------+---------------------------------|
                '-clustersize-'

Element	Purpose	Restrictions	Syntax
cluster-key column_name	The name of the column that is the cluster key	You can specify up to 16 columns to create a composite cluster key. You cannot specify a TEXT or BYTE data column as part of a cluster key. The maximum length of a cluster key is 390 bytes.	Identifier segment; see IBM Informix: Guide to SQL Syntax
cluster_name	The name of the optical cluster	The name must be unique.	Identifier segment; see IBM Informix: Guide to SQL Syntax
clustersize	The amount of optical platter space to allocate for the cluster, specified in kilobytes If no clustersize is specified, the size of the cluster defaults to 500 kilobytes.	The clustersize must be less than the volume size.	Expression segment; see IBM Informix: Guide to SQL Syntax
column_name	The name of the TEXT or BYTE data column(s) to be clustered	You can assign up to 16 distinct columns to a cluster.	Identifier segment; see IBM Informix: Guide to SQL Syntax
owner	The valid user name of the cluster	The specified name must be a valid user name.	Identifier segment; see IBM Informix: Guide to SQL Syntax

An optical cluster enables logically related TEXT or BYTE data to be stored on the same volume, which minimizes time-consuming platter exchanges during retrieval.

You can create (and, by default, become owner of) an optical cluster if you are the owner of the table, have the Resource privilege on the database and the Index privilege on the table, or have the DBA privilege on the database.

Only a person with DBA privileges can create the optical cluster and specify another user as the owner of the cluster.

CREATE OPTICAL CLUSTER (+, DB-Access, ESQL/C)

Syntax

Usage