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Re: Full table scan difference

From: Anjo Kolk <anjo_at_oraperf.com>
Date: Fri, 04 Apr 2003 16:58:38 -0800
Message-ID: <F001.0057B269.20030404165838@fatcity.com>


I wrote an LIO monitor, that should help to show what kind of LIO you are doing. It could help explain the difference in time. Give it a try and let me know what you see. Download it from oraperf.com

Anjo.

> List - As I mentioned earlier, a new manager came from a site that
regularly
> rebuilt tables. I protested the value of this, but his response was "well,
> at least you could test it." So on a test instance I've been doing a CTAS
to
> create a reorganized copy of the table in the same tablespace (LMT with
> uniform extents, autoextend on). As expected, the number of blocks is very
> close.
> Then I've been doing a FTS (select count(*)) on both tables. Usually
the
> time is very close. However, on one large table, the original is much
faster
> -- 18-sec. vs. 27-sec. 21,349 blocks vs. 21179. Same plan. Does anyone
have
> a theory for this discrepancy?
>
> Dennis Williams
> DBA, 40%OCP, 100% DBA
> Lifetouch, Inc.
> dwilliams_at_lifetouch.com
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: DENNIS WILLIAMS
> INET: DWILLIAMS_at_LIFETOUCH.COM
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Anjo Kolk
  INET: anjo_at_oraperf.com

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Received on Fri Apr 04 2003 - 18:58:38 CST

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