RE: Bizarre Cardinality
Date: Mon, 21 Apr 2008 14:52:21 -0700
One might not be the right answer, but it might be the CBO's best estimate based on your bind variables and the available statistics. The only way to know for sure what's going on is to look at a 10053 trace. Most likely if you have estimated cardinalities of 1, then you also have cartesian merge joins and buffer sorts and hence horrible performance when actual cardinality > 1. I don't see much point in guessing at it - just run the 10053 trace and see what's happening. You'll want to read this first if you haven't already read it:
From: Brady, Mark [mailto:Mark.Brady_at_Constellation.Com]
Using different parameters would explain why you might see different performance, but not why we would see all "one's".The plans would have 13 or 14 steps and at each and every step the cardinality would be 1. 1 wasn't the right answer for any bind variable.
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