Re: Optimizer in different ORACLE-Versions

From: <alcesteatxmissiondot_at_com.or.net>
Date: Thu, 10 Apr 2003 07:24:45 +0000 (UTC)
Message-ID: <b7367t$q0r$1@terabinaries.xmission.com>

Mladen Gogala <mgogala_at_adelphia.net> wrote:

>> is there a difference between the optimizer which comes with the ORACLE
>> Release 8.1.7 Standard Release and the optimizer which comes with the ORACLE

> The optimizer is the same, the only thing that is NOT the same are
> certain options. You cannot use function based indexes and partitions

Are you sure that the optimizer is identical, considering that the optimizer takes into account both function based indexes and partitions when developing query plans on EE? It would make sense if the steps which check for such situations would be skipped on SE. Why check to see if a function based index exists for your function when none is possible? Likewise for a bitmap index (and associated optimizations). On the other hand, it could simply never branch into that section of the optimizer code because it never sees those objects.

You all may be right...but it's a nitpicky question. Certainly it's safe to say that the optimizer behaves identically in situations where the objects it's dealing with are available on both editions. I'd be curious to know if the optimizer short-cuts those checks and/or excludes the code when normally it would be considering using EE-only features. Anyone know?

I admit to not knowing enough about the inner workings of the CBO to know if that would be a reasonable thing to do or not. I'm sure there are people who could shed light on that.

Jer Smith Received on Thu Apr 10 2003 - 02:24:45 CDT