RE: Estimate versus Compute
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: <ganstadba@xxxxxxxxxxx>, <mark.powell@xxxxxxx>, <Oracle-L@xxxxxxxxxxxxx>
- Date: Mon, 25 Jul 2005 11:51:37 -0700
Mike, I don't believe that is true. I recently reduced from compute to
estimate=25% and this reduced the runtime for update stats from 38 hours to 14
hours. I don't think it would make such a difference if it still had to visit
every block. I think you can specify whether your samples are based on rows or
blocks and Oracle will automatically compute if you specify estimate >= 50%.
Regards,
Brandon
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx]On Behalf Of Michael McMullen
Sent: Monday, July 25, 2005 11:28 AM
To: mark.powell@xxxxxxx; Oracle-L@xxxxxxxxxxxxx
Cc: klange@xxxxxxxxxx
Subject: Re: Estimate versus Compute
. . .
I read somewhere, can't remember where, that when estimating one should use
an estimate of 1 percent because anything else means all blocks get visited.
. . .
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