BUG #8130: Hashjoin still gives issues
От | stefan@konink.de |
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Тема | BUG #8130: Hashjoin still gives issues |
Дата | |
Msg-id | E1UXWS7-0007V8-N2@wrigleys.postgresql.org обсуждение исходный текст |
Ответы |
Re: BUG #8130: Hashjoin still gives issues
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Список | pgsql-bugs |
The following bug has been logged on the website: Bug reference: 8130 Logged by: Stefan de Konink Email address: stefan@konink.de PostgreSQL version: 9.2.4 Operating system: Linux Description: = We figured out that two very close query give a massive difference performance between using select * vs select id. SELECT * FROM ambit_privateevent_calendars AS a ,ambit_privateevent AS b ,ambit_calendarsubscription AS c ,ambit_calendar AS d WHERE c.calendar_id =3D d.id AND a.privateevent_id =3D b.id AND c.user_id =3D 1270 AND c.calendar_id =3D a.calendar_id AND c.STATUS IN ( 1 ,8 ,2 ,15 ,18 ,4 ,12 ,20 ) AND NOT b.main_recurrence =3D true; With some help on IRC we figured out that "there was a bugfix in hash estimation recently and I was hoping you were older than that", but since we are not: PostgreSQL 9.2.4 on x86_64-pc-linux-gnu, compiled by x86_64-pc-linux-gnu-gcc (Gentoo 4.7.2-r1 p1.6, pie-0.5.5) 4.7.2, 64-bit ...there might still be a bug around. We compare: http://explain.depesz.com/s/jRx http://explain.depesz.com/s/eKE By setting "set enable_hashjoin =3D off;" performance in our entire application increased 30 fold in throughput, which was a bit unexpected but highly appreciated. The result of the last query: http://explain.depesz.com/s/AWB What can we do to provide a bit more of information?
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