Re: Optimizer ignoring hints

From: Carlos Sierra <carlos.sierra.usa_at_gmail.com>
Date: Fri, 13 Sep 2013 06:27:42 -0500
Message-Id: <6A5B312C-10A5-4E80-B61C-2733793A07E2_at_gmail.com>



Or you can use SQLT XTRACT on both SQL_IDs and I will offer to take a look. MOS 215187.1 Cheers,

Carlos Sierra

blog: carlos-sierra.net
twitter: _at_csierra_usa

Life's Good!

On Sep 13, 2013, at 4:39 AM, jaromir nemec <jaromir_at_db-nemec.com> wrote:

> Hi,
>

>> However, if I put the statement in a script and replace the bind

> variables with SYSDATE ...
>
> This is a frequent source of confusion as a literal (here SYSDATE) is used
> in the statement instead of a bind variable, which can lead to a different
> (probably better) plan.
> You may try to explain plan using bind variables:
>
> EXPLAIN PLAN SET STATEMENT_ID = 'jara1' into plan_table FOR
> SELECT * from dual where dummy = :x;
>
>
> That should lead to the same (bad) execution plan, so you can start
> playing with hints and see their effect.
> Additionally, if you observe significant difference in the execution plan
> with BV and with literals you may proceed with topic as “BV peek” and
> “adaptive cursor sharing”
>
> HTH
>
> Jaromir D.B. Nemec
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
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Received on Fri Sep 13 2013 - 13:27:42 CEST

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