Re: Index problem
От
Tomasz Myrta
Тема
Re: Index problem
Дата
Msg-id
3F71CE4A.2090305@klaster.net
Ответ на
Index problem (Rigmor Ukuhe)
Список
Дерево обсуждения
Index problem "Rigmor Ukuhe" <rigmor.ukuhe@finestmedia.com>
Re: Index problem Tomasz Myrta <jasiek@klaster.net>
Re: Index problem "Matt Clark" <matt@ymogen.net>
Re: Index problem "Rigmor Ukuhe" <rigmor.ukuhe@finestmedia.com>
Re: Index problem Tom Lane <tgl@sss.pgh.pa.us>
Re: Index problem "Matt Clark" <matt@ymogen.net>
> Hi,
>
> I have a table containing columns:
>
> "END_DATE" timestamptz NOT NULL
> "REO_ID" int4 NOT NULL
>
> and i am indexed "REO_ID" coulumn.
> I have a query:
>
> select "REO_ID", "END_DATE" from "PRIORITY_STATISTICS" where "REO_ID" IN
> ('112851' ,'112859' ,'112871' ,'112883' ,'112891' ,'112904' ,'112915'
> ,'112924' ,'112939' ,'112947' ,'112960' ,'112984' ,'112999' ,'113013'
> ,'113032' ,'113059' ,'113067' ,'113084' ,'113096' ,'113103' ,'113110'
> ,'113117' ,'113125' ,'113132' ,'113139' ,'113146' ,'113153' ,'113160'
> ,'113167' ,'113174' ,'113181' ,'113188' ,'113195' ,'113204' ,'113268'
> ,'113279' ,'113294' ,'113302' ,'113317' ,'113340' ,'113358' ,'113385'
> ,'113404' ,'113412' ,'113419' ,'113429' ,'113436' ,'113443' ,'113571'
> ,'113636' ,'113649' ,'113689' ,'113705' ,'113744' ,'113755' ,'113724'
> ,'113737' ,'113812' ,'113828' ,'113762' ,'113842' ,'113869' ,'113925'
> ,'113976' ,'114035' ,'114044' ,'114057' ,'114070' ,'114084' ,'114094'
> ,'114119' )
>
> and it is _not_ using that index
>
> But following query (notice there are less id-s in WHERE clause, but rest is
> same)
>
> select "REO_ID", "END_DATE" from "PRIORITY_STATISTICS" where "REO_ID" IN
> ('112851' ,'112859' ,'112871' ,'112883' ,'112891' ,'112904' ,'112915'
> ,'112924' ,'112939' ,'112947' ,'112960' ,'112984' ,'112999' ,'113013'
> ,'113032' ,'113059' ,'113067' ,'113084' ,'113096' ,'113103' ,'113110'
> ,'113117' ,'113125' ,'113132' ,'113139' ,'113146' ,'113153' ,'113160'
> ,'113167' ,'113174' ,'113181' ,'113188' ,'113195' ,'113204' ,'113268'
> ,'113279' ,'113294' ,'113302' ,'113317' ,'113340' ,'113358' ,'113385'
> ,'113404' ,'113412' ,'113419' ,'113429' ,'113436' ,'113443' ,'113571'
> ,'113636' ,'113649' ,'113689' ,'113705' ,'113744' ,'113755' ,'113724'
> ,'113737' )
>
> will _is_ using index:
Why not. It's just because the second query is more selective. Probably
you don't have too many rows in your table and Postgres thinks it's
better (faster) to use sequential scan than index one.
Regards,
Tomasz Myrta
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