ch.sarada

• Jul 5th, 2005

 

hai sir, 
 
you have wrote oracle doesn't allow a user to specifically lacate the tables that's means.I didn't understand clearelly.please tell me that meaning 
thank u.

pavan

• Feb 27th, 2006

 

cluster is a private sql area where data stored more than one table.

use is fast retreving of data .

g_sidhu

 Profile 

• Feb 6th, 2008

 

Clustering is a method of storing tables that are intimately related and often joined together into the same area on disk. For example, instead of the BOOKSHELF table being in one section of the disk and the BOOKSHELF_AUTHOR table being somewhere else, their rows could be interleaved together in a single area, called a cluster.

VIKRAM

• Dec 18th, 2015

 

In this case does the cluster avoid the JOIN Condition or not?

sumanamara2016

 Profile Answers by sumanamara2016 

• Mar 18th, 2016

 

CLUSTERS
A cluster is a schema object that contains data from one or more tables
If you two are more tables are joined together on a single column and most of the time you issue join queries on them, then consider creating a cluster of these tables.
A cluster is a group tables that share the same data blocks i.e. all the tables are physically stored together.
For example EMP and DEPT table are joined on DEPTNO column. If you cluster them, Oracle physically stores all rows for each department from both the emp and dept tables in the same data blocks.
Since cluster stores related rows of different tables in same data blocks, Disk I/O is reduced and access time improves for joins of clustered tables.
Each cluster key value is stored only once each in the cluster and the cluster index, no matter how many rows of different tables contain the value.
Therefore, less storage might be required to store related table and index data in a cluster than is necessary in non-clustered table format.