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we are getting slowness after migrate from ORacle 10gr2 single db to Oracle 11204 oracle rac (standard ed) with asm, on oracle solaris 11. at this momento we have only one node. In the next days we will add another node. When a query run this take too much time if we compare with the old instance. Our RAC is now compose by one node and it has 3 dbs (dwh maximum 4tb, oltp and test db) Due to this we are implementing this: - we have run default statistics - we have rebuilded all indexes. - We will execute statistics with 100% for each object. - We activate osswbb and stastpack

We have put almost all the same parameters that we had in the old instance (10g). When I see my performance in EM it shows a lot of CPU wait when I digged into the causes it shows a lot of querys about an application schema that requires tunning. But there are a lot of them. The question is, why those querys in the old instance (10g single db) were works ok? and why in oracle rac 11gr2 don't ??

Any ideas ??

thank you.

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Are the query plans for the problem statements the same in your 10.2 database and your 11.2 database? Did you do anything as part of the upgrade to ensure plan stability? – Justin Cave Feb 26 '14 at 15:52
were the old statistics up to date? Did the explain plans - rows expected - match the actual rows returned? (in the 10g db) How are the qry's build (lots of stacked view or simple sql?) – ik_zelf Feb 26 '14 at 16:07
Was the 10gR2 also Standard Edition, or did you change from 10gR2 EE to 11gR2 SE RAC? – Colin 't Hart Jun 2 '14 at 7:26
How does the hardware compare? In particular, has your storage platform changed? – Colin 't Hart Jun 2 '14 at 7:27
If the execution plans aren't any different, then calculating statistics with 100% isn't going to help. – Colin 't Hart Jun 2 '14 at 7:29

Make sure you gathered statistics for fixed objects

SQL>exec dbms_stats.gather_fixed_objects_stats;

Create system stats.

– gather statistics while running a typical workload

Please have a look at this document


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