Re: a explain plan question
- From: "LS Cheng" <exriscer@xxxxxxxxx>
- To: rems@xxxxxxxx
- Date: Tue, 30 Jan 2007 17:17:51 +0100
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@xxxxxxxx> 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
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Remigiusz Sokolowski <rems@xxxxxxxx>
WP/PTI/DIP/ZAB (+04858) 52 15 770
MySQL v. 4.x
Oracle v. 10.x
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