Re: How "deterministic" are EXPLAIN PLAN results?

From: Richard Foote <richard.foote_at_bigpond.com>
Date: Wed, 9 Apr 2003 23:37:20 +1000
Message-ID: <GaVka.10623$1s1.170940@newsfeeds.bigpond.com>

"Larry Leonard" <Spam_at_DefinitiveSolutions.com> wrote in message news:27270a53.0304090254.6c48b3f_at_posting.google.com...
> I have a question about Oracle's "explain plan". Let's set aside the
> subject of "stored outlines" for the moment, and assume that I'm
> talking about only one database (that is, I'm not talking about
> anything *across* databases).
>
> Let's say I have a SELECT statment, and I'm considering using one of
> two hints (call them HINTA and HINTB, to avoid clouding the issue).
> When I run the SELECT with HINTA, I can get the "explain plan" for it
> from my PLAN_TABLE. Likewise for running the SELECT using HINTB. So
> far so good.
>
> My question is this. If the "explain plan" for these two queries is
> *exactly* the same, does that mean that Oracle will *definitely* use
> the same "statement execution plan" for them? Or are there ever
> circumstances in which two SELECT statements with identical "explain
> plans" will be executed with different "statement execution plans"?
>

Hi Larry,

If I understand your question correctly, the answer is yes, Oracle will use the same "statement execution plan".

Cheers

Richard Received on Wed Apr 09 2003 - 08:37:20 CDT