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Message Posted: Mon, 21 Jun 2004 @ 07:41:09 GMT


     
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Subj:   Estimated I/Os shows up as NEGATIVE in SI
 
From:   Anomy Anom

<-- Anonymously Posted: Sunday, June 20, 2004 20:31 -->

I have been trying to performance tune a query which basically joins 3 or 4 tables and runs between 1 hour to 2 hours.

I recreated all these tables with the same data and same statistics in another database and it ran in 7 mins. Confused as to what could be wrong. My first step in to run CheckTable for all these Tables, which is in progress.

However when the original job runs I see the following figures in Session Information.

        Est I/Os           Actual I/Os
      -526221312              13786122
       -81372160              17703380
      -795344896                 32817
     -1920991232          Not recorded

How is the figure Estimated I/Os generated. Is it dependent on COLLECT STATS?

Why is this number showing as NEGATIVE? Whereas when it runs the Actual I/Os is a positive number.

Any insights much appreciated.

Thanks



     
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