Re: Analyze table compute statistics adversely affects optimizer?

From: Gjlinker <gjlinker_at_aol.com>
Date: 07 Feb 1999 09:22:40 GMT
Message-ID: <19990207042240.11568.00000379@ngol03.aol.com>

Dear all,

>Could this cause the database to switch which optimizer it uses, cost based
>as opposed to rule based.

>What is going on?

I had similar problems. Performance was reasonable without any statistics produced. After COMPUTE STATISTICS Oracle7 choose the wrong execution plans.

I called Oracle support and to my big surprise they answered that the Oracle optimizer is not working properly in Oracle7. In Oracle 8 we are getting a complete rewrite of the optimizer so relying on it is not wise.

He adviced me NEVER to COMPUTE STATISTICS but to use optimizer hints in my SQL to be explicit which index should be used etc.

Regards Gerrit-Jan Linker,

---

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Received on Sun Feb 07 1999 - 03:22:40 CST