Re: Slow indexscan

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От Oleg Bartunov
Тема Re: Slow indexscan
Дата
Msg-id Pine.LNX.4.64.0706202152250.1881@sn.sai.msu.ru
обсуждение исходный текст
Ответ на Re: Slow indexscan  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-performance
Mikko,

I don't follow this thread, just see familiar spherical coordinates we
work with a lot. If you need fast radial query you can use our
q3c package available from q3c.sf.net. See some details
http://www.sai.msu.su/~megera/wiki/SkyPixelization

Oleg

On Wed, 20 Jun 2007, Tom Lane wrote:

> "Mikko Partio" <mpartio@gmail.com> writes:
>
>>  Index Scan using tbl_20070601_pkey on tbl_20070601 t1
>> (cost=0.00..365.13rows=13 width=137) (actual time=
>> 120.83..10752.64 rows=539 loops=1)
>>    Index Cond: ((validtime >= 20070602000000::bigint) AND (validtime <=
>> 20070602235500::bigint) AND (latitude = 60.2744::double precision) AND
>> (longitude = 26.4417::double precision))
>>    Filter: (parname = 'temperature'::character varying)
>
> You do realize that's going to scan the entire index range from
> 20070602000000 to 20070602235500?
>
> If this is a typical query you'd be better off putting the lat/long
> columns first in the index.
>
>             regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Have you searched our list archives?
>
>               http://archives.postgresql.org
>

     Regards,
         Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83

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