Re: stupid question on FTS
- From: Vasu <vasudevanr@xxxxxxxxx>
- To: "Uzzell, Stephan" <SUzzell@xxxxxxxxxx>
- Date: Fri, 24 Aug 2012 08:30:25 -0500
I think I am in a similar situation , as the stats became stale after
adding 50% more rows to the table .
I got the stats done by referring to the article by Doug.. and the list of
useful pointers are here.
http://jonathanlewis.wordpress.com/2010/03/17/partition-stats/
I am able to get the desired access path through hints, but not so lucky at
times. Though I don't expect a FTS on that table, its a close call..and
optimizer may still be correct, as the specific SQL JOINing that table is
inspecting less than 10% rows. I have all the necessary Indexes and the
Rule-Based optimizer would have chosen the expected path (Favoring the
index..than FTS ).
Will do additional analysis based on the inputs and share the results.
Thanks
On Fri, Aug 24, 2012 at 8:09 AM, Uzzell, Stephan <SUzzell@xxxxxxxxxx> wrote:
> Are you seeing an FTS on the whole table? Or on a partition?
>
> We've seen something similar - with a very large table with monthly
> partitions. It *seems* to us that the 10g stats job that collects stale
> stats looks at the table as a whole, not the partition. Because the new
> monthly partitions are so small relative to the table, they don't trigger
> the collect stale stats job. Therefore Oracle has no stats on the new
> partitions, thinks they are tiny, thinks the FTS will be cheap, and chooses
> that over a more appropriate index scan.
>
> We're still working on how to best manage statistics for the new
> partitions...
>
> Stephan Uzzell
>
> -----Original Message-----
> From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
> On Behalf Of Vasu
> Sent: Thursday, 23 August, 2012 20:35
> To: oracle-l@xxxxxxxxxxxxx
> Subject: stupid question on FTS
>
> I have a huge table in my OLTP DB, that has 100 million+ rows (pls don't
> ask why), and is partitioned.
> I know it doesn't make sense for my App to ever do a FTS on it.. But
> Oracle at times picks up FTS as the best access path (and our STATS is not
> at it best yet).
>
> It just wished for a setting..that "I never want to have a FTS on my
> table..Unless otherwise explicitly told thru a Hint" .
>
> yes, a Hint/setting can't compensate for lack of STATS.. but just that my
> desparate situation/laziness forced me to think that way.
>
> Any thoughts?
>
> Thanks,
> Vasu
>
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
--
-Vasu
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