RE: Join cardinality and query tuning.

Can you run a 10053 event trace and post the trace? It will show all the statistics and values the optimizer uses to calculate the join cardinality. Maybe that will shed some light on the "mystery". I have seen many cases where the CBO's join selectivity calculation is different from the formula you use, which you got from my paper and which I got from a metalink note.

Quoting Charu Joshi <joshic_at_mahindrabt.com>:

>
> Thanks Lex,
>
> Then why is the row-source cardinality shown in the Explain Plan radically
> different from the one calculated using this formula (Please refer to my
> original post.)? Is there any silly mistake in my calculations (I quite am
> prone to that.)?
>

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regards

Wolfgang Breitling
Oracle 7,8,8i,9i OCP DBA
Centrex Consulting Corporation
www.centrexcc.com

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