Re: Same Query, same database, same application, new plan from one environment but not from another

  • From: "Rumpi Gravenstein" <rgravens@xxxxxxxxx>
  • To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 28 Aug 2008 22:46:55 -0400

I've got the results of the traces back and it looks like the Access code is
now passing a date bind variable in as something that prevents the proper
use of the indexed date column.  I say this because when I look at the trace
I see the internal_function on the indexed column and when I run the query,
with the only modification being adding 0 to the date column I get my bad
explain plan.

What's perplexing is that everyone claims that there were no changes made.
What I know for sure is that there was an upgrade to a new release of the
Oracle Windows ODBC driver -- 10.2.0.4 ( supposedly migrated a few weeks
prior to our problem start) and that the Oracle statistics collection
procedure was changed from a 30% estimate to COMPUTE on the day the problem
was first reported.


On 8/27/08, Rumpi Gravenstein <rgravens@xxxxxxxxx> wrote:
>
> <snip>
> 10g stores previous version of stats for 30 days by default, you can
> revert stats to see if the better performing plans return and if so
> you can compare the different versions of the stats and plans to
> identify the culprit and correct it.
> </snip>
>
> The queries from the two environments are run within a few minutes of each
> other, sometimes the Toad version first and sometimes the Access version.
> Each run uses the same, single bind value.  Given that I can't see how the
> problem can be related to differences in statistics.
>
> I'll check meta-link for odbc slow-down bugs.
>



-- 
Rumpi Gravenstein

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