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Message Posted: Thu, 18 Nov 2004 @ 16:49:46 GMT


     
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Subj:   Re: PMON explain for running query - Large discrepancy between "Estimated I/O" and "Actual I/O"
 
From:   Anomy Anom

<-- Anonymously Posted: Thursday, November 18, 2004 11:45 -->

Hi,

Is there any documentation as to what is "estimated I/O" and what is "actual I/O" from the point of estimated & actual rows. Does "estimated I/O" denote estimated rows in the explain and "actual I/O" denote rows in the explain. If not what is used to determine these values. I see many a time that the actually returned rows are actually the "actual I/O", that is why the doubt. I also know that it is very hard to estimate the I/Os specifically during estimation, so it must be determined from the estimated rows.

Please clarify, I would really like to understand the details.


Great Thanks.



     
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