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we recently upgraded our db from 11g to 12c, now db with 12.2 version on linux. the db is mostly of oltp type, having around 150GB application data and tables having approx 5GB to 10Gb in size, after upgradation the performance of db is degraded, we believe we can improve that by changing db parameters. Can you pls suggest any oracle parameters to look for to improve performance apart from memory related. and any parameters specific to 12.2 version ?

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RUDRA PARIDA
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    Seems like too broad a question, and not really on-topic for this site. But the first thing to check is that your table and index statistics are up-to-date. – Alex Poole Jul 08 '20 at 09:12
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    I agree with @AlexPoole. You need to check the ADDM reports (if you have Tuning Pack licensed) or Perfstat results to find out where your database bottlenecks actually are. Random changes to DB parameters will not help without knowing more precisely what you're trying to fix. Is it slow because you need more memory, or because you're processing extra disk i/o? Because you need more indexes or because you have too many? Because you're parsing SQL inefficiently or committing changes too often? There are about 100 more possibilities on top of just those, and each will have a specific fix action. – pmdba Jul 08 '20 at 17:03
  • Thanks , I will check to run awr and addm, but my query was like , the db having same data on both the versions, even data and counts also same, so the question came to my mind like any parameter changes will benefit ? – RUDRA PARIDA Jul 09 '20 at 14:32

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Please check wehat is the value of parameter OPTIMIZER_FEATURES_ENABLE i.e. whether you are using 11g optimizer of 12c optimizer. Sometimes 12c optimizer dont perform well along with that check the values of OPTIMIZER_ADAPTIVE_PLANS and OPTIMIZER_ADAPTIVE_STATISTICS. Please refer to this article. I have faced a similar performance issue after migration from 11g to 12.2c, so please share yur feedback after checking these parameter values.

Atif
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  • Thanks Asif, For us both the parameters are default. I will check if any changes are helping us, Thanks for this article. – RUDRA PARIDA Jul 13 '20 at 14:44