RE: DB performance after upgrade from 9i to 11gR2

Also check whether you are getting adaptive direct read, which has pros and cons, especially as regards multi-piece rows and things like delayed block cleanout.  

Read all about it on Frits Hoogland's blog. I think JL has written some about this was well.  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Powell, Mark
Sent: Thursday, May 08, 2014 9:10 AM
To: oracle-l_at_freelists.org
Subject: RE: DB performance after upgrade from 9i to 11gR2  

BA, what kind of memory management is in use. You said the plans look good but the queries just do not complete so this makes me wonder if the system is waiting on AMM memory management operations to complete.  

Have you checked the disk performance?  

What about other OS measures: cpu utilization and memory?      

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Bheemsen Aitha
Sent: Thursday, May 08, 2014 2:40 AM
To: oracle-l_at_freelists.org
Subject: DB performance after upgrade from 9i to 11gR2  

Hello DBA gurus,  

We recently upgraded our database from 9i to 11gR2 on Solaris 11 64-bit, Veritas File system (single instance). We tested thoroughly in our QA environment before the upgrade. But after the upgrade we are seeing terrible performance in production with many of the queries. Even though the query plan looks good with very low cost, the queries are just sitting there and not finishing. Some of the queries have differences in plan (FTS to index scans on small tables) when compared to QA environment. We gathered stats with default auto sample size and default method_opt options. I opened a ticket with oracle on the performance issue, but I doubt if I can get a solution on this. The QA and prod environments are exactly same, but the queries are running are faster in QA. Did anyone come across similar problem in the past? Any inputs are greatly appreciated.    

Thanks

BA  

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