Curious performance experiment

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From: JXStern (JXSternChangeX2R_at_gte.net)
Date: 11/03/04 

Date: Wed, 03 Nov 2004 07:34:53 -0800

I found an SP scanning a table of 100k rows which lacked the proper
index, doing a join to several other tables. Statistics IO reported
it took 26000 logical reads (to do it twice, btw).

I then added the proper index. Reads dropped to 1500. Good, huh? I
should have declared victory and gone home.

But no, not me. I then dropped the index and reran. It went up
again, of course, but only to 6700 reads.

Um, ... anyone ever see anything like this? I'm at something of a
loss. I thought I'd run it several times in each mode, and in fact
was running it in a loop of 100 from query analyzer to get a decent
clock-time idea of execution (but got the statistics IO from single
executions).

Josh

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