RE: Skip scans

 In 9i skip scan is turned on automatically without the necessity of the = hint. Under 9.2.0.3 we had to turn it off as the optimizer was choosing = it when other more usable indexes were avaialable. In 9.2.0.5, it = appears more stable. However, for simple performance it is useful in low = usage scenarios, (the query is not executed that often and you don't = have space to burn). Under heavy usage it is much more efficient to = simple build the index you need versus incurring the block buffer hit = from the skip scan.

-----Original Message-----

From: oracle-l-bounce_at_freelists.org =
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Mladen Gogala Sent: Wednesday, December 29, 2004 10:47 AM To: 'Oracle-L (E-mail)'
Subject: Skip scans

Is anybody using index skip scan feature? What would be a situation in = which the feature should be used? I have a SQL statement, part of ETL = process that I have to tune. The initial reuslts are encouraging = although not dramatic. Does anybody else have any type of practical = experience with skip scans and index_ss hint?

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Mladen Gogala
Oracle DBA
Ext. 121

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http://www.freelists.org/webpage/oracle-l Received on Thu Dec 30 2004 - 02:49:37 CST