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Home -> Community -> Mailing Lists -> Oracle-L -> RE: use of reverse key index,cost based optimizer
helpdesk
I don't see where anyone responded. If you look up reverse key index in the documentation, it says something about if you have a column where most of the values have leading values that are close. Reverse key will help the btree of the index be more balanced. That helps on queries. And on inserts you aren't continually hitting the same block, but spreading the inserts.
Oracle has two SQL optimizers, rule-based and cost based. The cost based is more sophisticated. You first populate statistics on your tables. When creating an execution plan for your SQL the CBO will consider those statistics. Does that answer your questions?
Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
Sent: Friday, May 30, 2003 1:25 AM
To: Multiple recipients of list ORACLE-L
hai gurus
please tell use of using reverse key index
and what exactly cost based optimizer
thanks in advance
manjunath
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Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services ---------------------------------------------------------------------To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Fri May 30 2003 - 14:09:52 CDT
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