Re: Strange behaviour of Cramer query

From: Gerard H. Pille <>
Date: Fri, 26 Jun 2009 17:45:56 +0200
Message-ID: <4a44ed34$0$2854$>

HansPeter schreef:
> Hello,
> A lot has been said sofar.
> To make things clearer.
> The statement I execute has 2 bind variables. Every execution uses the
> same bind variables.
> The big difference in wait events is
> Event waited on Times Max. Wait Total
> Waite
> direct path write temp 53363
> 0.18 14.53
> direct path read temp 298016 0.61
> 607.8
> The direct path events are not present in the quick case.
> But the main problem is why are these present in execution N but not
> in execution N-1.
> Some people suggest that this is due to caching. But that does not
> make sence because the query is also slow after a quick execution a
> second before.
> Furthermore the caching does not apply to temp segments.
> It just makes no sense that the same execution plan with the same bind
> variable and the same rows that are yielded suddenly shows
> 9 million processed rows for certain row source operations and next
> time 0 rows and the next time 9 million rows again.
> Looks like a bug to me.
> regards HansP

Watch out with the explain plans returned by tkprof. They may not be the same plan as was used during execution. Next time it is slow, use dbms_xplan, there is plenty of time ;-), just to make sure.

About "direct path read temp", read

Gerard Received on Fri Jun 26 2009 - 10:45:56 CDT

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