Re: Things to consider during upgrade/migration

  • From: Mladen Gogala <gogala.mladen@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 17 Nov 2021 15:53:39 -0500

On 11/17/21 12:28, Lok P wrote:
Yes Mark, so my point was, we already have ~9 sqls which are using baseline in current 11.2. version and of course have optimizer_use_sql_plan_baselines set as TRUE(which is default). But Now that we will be setting optimizer_capture_sql_plan_baselines to TRUE a few days before 19C upgrade on production to get hold of all the possible sql and their plans(say we captured ~1000 sqls baseline), but we don't want all of those to be enabled at that same moment. rather we want only to enable the baseline for those ~9 old sqls + additional few sql (say e.g. 3 sqls ) which misbehaved/changed plan post upgrade to 19c. And we want to drop/get rid of those other ~997 sql baselines from our 19C version database (which we captured initially just for our safety). So considering its inplace upgrade and we don't have an exact test environment like RAT, is there a way to achieve this in the existing production database? I am still unable to get it clearly.

Well Lok, the way I see it, you're in the so called "Bridge of Death" situation.

Must answer these questions three, the other side to see. And these questions are about your SQL. The only way you will answer the questions is by testing. Test, test and then test again. And then retry the answers to the questions three. Nobody can give you the exact recipe how to migrate your database.  Well, you have to know these things when you're a DBA. Think of the brave Sir Robin and start testing.

Mladen Gogala
Database Consultant
Tel: (347) 321-1217
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