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April 20, 2012

IOT Candidates – Which tables should be consider to Index Organizer Tables

Filed under: Uncategorized — heliodias @ 9:32 pm

Abstract: This post is an introduction to where the investigation should start.

The very begin is check tables with just one index:

SELECT COUNT(*) FROM (
select OWNER,TABLE_NAME,count(*) from dba_indexes
WHERE OWNER NOT IN (‘SYS’, ‘SYSMAN’,’XDB’,’SYSTEM’,’CTXSYS’,’OLAPSYS’)
group by OWNER,TABLE_NAME
HAVING COUNT(*)=1);

  COUNT(*)
———-
      2008

In this sample we could see 2008 tables that  deserve a further investigation.

The next step is check the  v$segment_statistics to see which among them have less DML , those will be the perfect candidate.

Important advice, before change the structure to IOT, test it, and be sure that you won´t gonna need lot´s of  indexes in the future.

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