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Re: a explain plan question

From: LS Cheng <exriscer_at_gmail.com>
Date: Tue, 30 Jan 2007 17:17:51 +0100
Message-ID: <6e9345580701300817u2c44058bkba7afa803e8b7460@mail.gmail.com>


doesnt look very good plan

TUD_FEDIA is accessed first then from that it eliminates partitions (partition start/stop KEY), the problem seems nested loop, how many rows is TU_FEDIA returning?

On 1/30/07, Remigiusz Soko?owski <rems_at_wp-sa.pl> wrote:
>
>
> >
> > Execution Plan
> > ----------------------------------------------------------
> > 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1022392 Card=934
> > Bytes=49502)
> > 1 0 SORT (GROUP BY) (Cost=1022392 Card=934 Bytes=49502)
> > 2 1 NESTED LOOPS (Cost=814767 Card=182275095 Bytes=9660580035)
> > 3 2 TABLE ACCESS (FULL) OF 'TUD_FEDIA' (Cost=3 Card=30
> > Bytes=480)
> > 4 2 PARTITION RANGE (ITERATOR)
> > 5 4 TABLE ACCESS (FULL) OF 'TUH_NVPAGINA' (Cost=27159
> > Card=5992606 Bytes=221726422)
> >
> > I was wondering how to read this plan, the order of steps. From old
> > set autotrace trace exp it seems to me that step 5 is the first step?
> >
> > 5 4 TABLE ACCESS (FULL) OF 'TUH_NVPAGINA' (Cost=27159
> > Card=5992606 Bytes=221726422)
> >
> AFAIK the first most nested line is the first line (in this example the
> one indicated by You)
>
> Regards
> Remigiusz
>
> --
> ---------------------------------------
> Remigiusz Sokolowski <rems_at_wp-sa.pl>
> WP/PTI/DIP/ZAB (+04858) 52 15 770
> MySQL v. 4.x
> Oracle v. 10.x
> ---------------------------------------
>
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>

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Received on Tue Jan 30 2007 - 10:17:51 CST

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