Oracle-L: Re: Oracle's use of Indexes

From: Mark Richard <mrichard_at_transurban.com.au>
Date: Thu, 18 Sep 2003 16:49:51 -0800
Message-ID: <F001.005D06AE.20030918164951@fatcity.com>

Does the query hit any other tables? If so, a different statistic somewhere else might be influencing the optimisor. Otherwise certain session / init parameters can influence the optimisor (multiblock read count, block size even) - Sometimes it can be difficult to track down the culprit but you should be able to find differences somewhere.

                                                                                                                                      
                      Craig Munday                                                                                                    
                      <cmunday_at_bigpond.        To:       Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>                  
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                      Sent by:                 Subject:  Re: Oracle's use of Indexes                                                  
                      ml-errors_at_fatcity                                                                                               
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                      19/09/2003 00:54                                                                                                
                      Please respond to                                                                                               
                      ORACLE-L

Craig,

Just out of interest, what type of application is running on the database? I was just wondering why you were not using the plan stability features in 8i on your production database.

Regards,
Craig Munday.

At 05:45 AM 2/06/2003 -0800, Craig Healey wrote:
>OK, I'm confused. Maybe it's Monday morning and my brain's not working.
>We have a production schema and a test schema on the same Oracle 8.1.7
>instance, running on Windows. They both have a customer table, with 3
>million and 2 million records respectively. They both have the same
>indexes, and both have been analyzed today. Production used an index and
>took 40ms. Test didn't and took 20s. I played around, analyzing,
>dropping and creating indexes etc. Now neither of them use the index,
>both taking around 20s.
>I can add a hint, which works, but I want to know what changed.
>
>TIA
>
>Craig Healey
>
>
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Received on Thu Sep 18 2003 - 19:49:51 CDT