Re: Why is the full table scan not being chosen?

  • From: "Paul Vallee" <paulvallee@xxxxxxxxx>
  • To: gorbyx@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
  • Date: Wed, 5 Jul 2006 09:14:42 -0400

Do you have you optimizer_mode set to first_rows by any chance?
IIRC, this way optimizer will always choose index scan if that helps
to avoid sorting - regardless of the cost.

DBFMRC=8. OPTIMIZER_MODE=FIRST_ROWS. 

Looks like that's it!

Paul



On 7/5/06, Alex Gorbachev <gorbyx@xxxxxxxxx> wrote: 

(retry due to overquote...)

Do you have you optimizer_mode set to first_rows by any chance?
IIRC, this way optimizer will always choose index scan if that helps
to avoid sorting - regardless of the cost.


2006/7/5, Stuart Clowes <stuart.clowes@xxxxxxxxx>:
> So, it looks to me like the FTS is cheaper, and the optimizer knows it.
So
> why doesn't it choose it unless I ask it to?


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Alex Gorbachev

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Paul Vallee
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