Re: Strangely Variable Query Performance
От | Scott Marlowe |
---|---|
Тема | Re: Strangely Variable Query Performance |
Дата | |
Msg-id | 1176416077.13754.26.camel@state.g2switchworks.com обсуждение исходный текст |
Ответ на | Re: Strangely Variable Query Performance (Steve <cheetah@tanabi.org>) |
Ответы |
Re: Strangely Variable Query Performance
Re: Strangely Variable Query Performance |
Список | pgsql-performance |
On Thu, 2007-04-12 at 17:04, Steve wrote: > >> Seq Scan on detail_summary ds (cost=0.00..1902749.83 rows=9962 width=4) > >> Filter: ((receipt >= '1998-12-30'::date) AND (encounter_id = ANY > >> ('{8813186,8813187,8813188,8813189,8813190,8813191,8813192,8813193,8813194,8813195,8813196,8813197,8813198,8813199,8813200,8813201,8813202,8813203,8813204,8813205,8813206,8813207,8813208,8813209,8813210,8813211,8813212,8813213,8813214,8813215,8813216,8813217,8813218,8813219,8813220,8813221,8813222,8813223,8813224,8813225,8813226,8813227,8813228,8813229,8813230,8813231,8813232,8813233,8813234,8813235,8813236,8813237,8813238,8813239,8813240,8813241,8813242,8813243,8813244,8813245,8813246,8813247,8813248,8813249,8813250,8813251,8813252,8813253,8813254,8813255,8813256,8813257,8813258,8813259,8813260,8813261,8813262,8813263,8813264,8813265,8813266,8813267,8813268,8813269,8813270,8813271,8813272,8813273,8813274,8813275,8813276,8813277,8813278,8813279,8813280,8813281,8813282,8813283,8813284,8815534}'::integer[]))) > >> (2 rows) > > > > How accurate is the row estimate made by the planner? (explain analyze > > to be sure) > > > > Results: > > Seq Scan on detail_summary ds (cost=0.00..1902749.83 rows=9962 width=4) > (actual time=62871.386..257258.249 rows=112 loops=1) > Filter: ((receipt >= '1998-12-30'::date) AND (encounter_id = ANY > ('{8813186,8813187,8813188,8813189,8813190,8813191,8813192,8813193,8813194,8813195,8813196,8813197,8813198,8813199,8813200,8813201,8813202,8813203,8813204,8813205,8813206,8813207,8813208,8813209,8813210,8813211,8813212,8813213,8813214,8813215,8813216,8813217,8813218,8813219,8813220,8813221,8813222,8813223,8813224,8813225,8813226,8813227,8813228,8813229,8813230,8813231,8813232,8813233,8813234,8813235,8813236,8813237,8813238,8813239,8813240,8813241,8813242,8813243,8813244,8813245,8813246,8813247,8813248,8813249,8813250,8813251,8813252,8813253,8813254,8813255,8813256,8813257,8813258,8813259,8813260,8813261,8813262,8813263,8813264,8813265,8813266,8813267,8813268,8813269,8813270,8813271,8813272,8813273,8813274,8813275,8813276,8813277,8813278,8813279,8813280,8813281,8813282,8813283,8813284,8815534}'::integer[]))) > Total runtime: 257258.652 ms So there's a misjudgment of the number of rows returned by a factor of about 88. That's pretty big. Since you had the same number without the receipt date (I think...) then it's the encounter_id that's not being counted right. Try upping the stats target on that column and running analyze again and see if you get closer to 112 in your analyze or not.
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