RE: How many is too many
Date: Fri, 12 Aug 2011 06:58:57 -0500
Message-ID: <C5533BD628A9524496D63801704AE56D6A315EC6F9_at_SPOBMEXC14.adprod.directory>
Sometimes, a "good" index causes exceptionally bad performance. We have a situation where if I add, what I "think" is, a good index on paper, the execution plan changes in such a way as to make subsequent queries perform horribly. The physical I/O looks good, the cost looks good, but the logical I/O goes berserk.
Chris Taylor
Sr. Oracle DBA
Ingram Barge Company
Nashville, TN 37205
Office: 615-517-3355
Cell: 615-663-1673
Email: chris.taylor_at_ingrambarge.com<mailto:chris.taylor_at_ingrambarge.com>
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From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Ram Raman
Sent: Thursday, August 11, 2011 3:45 PM
To: ORACLE-L
Subject: How many is too many
Listers,
I am looking at a table in our system and it has 12 indexes, we are planning on adding another one. I am aware of the effects of having too many indexes, but in this case adding an extra index helps a certain query that runs slow. Other queries and most other operations against the table are acceptable too. I see a few tables like this; is there a number above which is considered a no-no when it comes to adding more indexes.
PS. The tables and queries are structured in a way that seem to require several indexes - it is a third party product.
TIA,
Ram.
-- http://www.freelists.org/webpage/oracle-lReceived on Fri Aug 12 2011 - 06:58:57 CDT