Re: Optimizer/query plan issue

We encontered a similar problem going to V4R4, and had endless problems
with simple Queries and SQL statements taking hours instead of minutes.
In the end we deleted all the indexes and rebuilt them.
Also applied all the DB2/SQL PTF's

Hope that's relevant....

Sam.




Jim.Nelson@RCIS-NET.COM@midrange.com on 03/08/2001 20:30:54

Please respond to MIDRANGE-L@midrange.com

Sent by:  owner-midrange-l@midrange.com


To:   MIDRANGE-L@midrange.com
cc:
Subject:  Optimizer/query plan issue



We have been struggling for two months with the following:

Upgraded to V4R5, and immediately started having performance difficulties.
After a great runaround with IBM support, two problems were identified.
* Optimizer is deciding to rebuild the access plan for seemingly no reason
* After the access plan is rebuilt, the operating system is unable to save
the new plan.  The system cannot gain a 'lock' on the object, even though
nobody else is running the stored procedure at that moment.

We've loaded several ptfs, some to allow IBM to better monitor our system,
and some to try and reduce the instances that the optimizer decided to
rebuild the plan.  The number of rebuilds has been reduced some, but it
still too high (hundreds per day), and we are not yet able to save the
plan.
This causes every instance of that stored procedure to perform very poorly
(what would take .03 seconds now takes 17.0 or more) the rest of the day.

Has anybody experienced similar problems?  If so, are you getting anywhere
on it?  We've been reduced to shutting down/restarting QSRV nightly and, on
a dedicated system, running all of our stored procedures.  This will put
them back 'on track', and prepare us for the day - until they start falling
out again.

I'm running out of ways to explain this to users and Sr. Management.  Any
suggestions would be welcome.

Thanks, JN
+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to MIDRANGE-L@midrange.com.
| To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com.
| To unsubscribe from this list send email to
MIDRANGE-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator:
david@midrange.com
+---



+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to MIDRANGE-L@midrange.com.
| To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com.
| To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---