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From Kristian Waagan <kristian.waa...@oracle.com>
Subject Re: XPLAIN and statement recompilation (invalidation)
Date Thu, 14 Oct 2010 09:05:03 GMT
  On 14.10.10 03:46, Bryan Pendleton wrote:
>> The result of the above event is that an entry for the query is added
> > twice to SYSXPLAIN_STATEMENTS; once when the recompilation
>> of the query is triggered, and once when the query has completed.
>
> This surprises me. I don't understand why re-compilation of the query
> is getting all the way to the execution phase; I would have expected
> the compilation to be performed without ever opening and closing
> execution-phase result sets.
>
> I think it would be great if you could log this and even better if
> we could come up with a simple and predictable test case that 
> demonstrates
> it, as it sounds like the index statistics technique is somewhat
> unpredictable.

Hi Bryan,

I don't think I'll have time to follow up on this now, but I have logged 
it as DERBY-4849 and attached the little information I have to that JIRA 
issue.
Unfortunately, I don't know how to reproduce this easier at this point.


-- 
Kristian

>
> This is a very interesting finding, and thanks for tracking
> it down and raising it!
>
> bryan


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