Full table scan difference

From: DENNIS WILLIAMS <DWILLIAMS_at_LIFETOUCH.COM>
Date: Fri, 04 Apr 2003 12:49:22 -0800
Message-ID: <F001.0057AD09.20030404124922@fatcity.com>

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
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Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM

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