Re: a explain plan question

To answer the original question about how to identify the first operation that could be considered for execution, Dan Fink's answer is an excellent explanation - but for an easier mechanism, I've just posted something about it on my blog at

    http://jonathanlewis.wordpress.com/all-postings

In fact, Dan's answer needs a little corollary - as a plan can contain conditional execution paths:

    http://jonathanlewis.wordpress.com/2007/01/09/conditional-sql/

so his comment needs a further messy expression wrapped around it discussing the possibility of when an entire subplan may or may not be executed at run-time.

Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com

Author: Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

The Co-operative Oracle Users' FAQ
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• Original Message ----- From: "FreeLists Mailing List Manager" <ecartis_at_freelists.org> To: "oracle-l digest users" <oracle-l_at_freelists.org> Sent: Wednesday, January 31, 2007 7:05 AM Subject: oracle-l Digest V4 #31

> ------------------------------
>
> Date: Tue, 30 Jan 2007 15:43:31 +0100
> From: amonte <ax.mount_at_gmail.com>
> Subject: a explain plan question
>
> Hi
> I have this query
>
> SELECT
> TUH_NVPAGINA.ID_SECCION AS ID_SECCION,
> TUD_FEDIA.ID_TIPO_DIA AS ID_TIPO_DIA,
> TUD_FEDIA.ID_MES AS ID_MES,
> count(distinct TUH_NVPAGINA.TX_COOKIE_SESION) CNT
> FROM
> TUH_NVPAGINA,
> (SELECT FE_DIA, ID_MES, ID_TIPO_DIA
> FROM TUD_FEDIA
> WHERE ID_MES = :p_f_inicio) TUD_FEDIA
> WHERE TUH_NVPAGINA.FE_DIA = TUD_FEDIA.FE_DIA
> GROUP BY
> TUH_NVPAGINA.ID_SECCION,
> TUD_FEDIA.ID_TIPO_DIA,
> TUD_FEDIA.ID_MES
>

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