Optimizer

It’s always the Optimizer, isn’t it?! – Part 1

Wouldn’t you agree?

My colleagues from the Optimizer Development might forgive me but a lot of people would say: “Everything went fine after upgrade – except for those tiny 3 queries!”. And I know, you have tested a lot. I’d like to tell you about a few issues we’ve seen post upgrade with 11.2.0.2.

  1. You have captured your plans in Oracle 10.2 pre-upgrade.
  2. You have moved these plans from your SQL Tuning Set into the SQL Plan Baseline in Oracle 11.2.
  3. But the optimizer doesn’t pick them although you have:
    (a) ACCEPTED and
    (b) FIXED them.

Why?

It …

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Optimizer patch recommendation for Oracle 11.1.0.7

Thanks to Thomas Kempkens from Oracle’s ACS Support who brought this to my attention:

This will just apply to 11.1.0.6 and 11.1.0.7 customers:
It is possible to get an ORA-979 for a query containing a subquery with an aggregate and no group by.
This issue is known as bug7189491 (non-public) – there are one-offs (single patches) available on top of 11.1.0.7 for Linux (32/64bit) and Solaris.
If you’ll still get an ORA-979 then you might set _optimizer_group_by_placement to false

You’ll find further information in Note:8260094…

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