Re: Strange workaround for slow query

Поиск
Список
Период
Сортировка
От Harald Fuchs
Тема Re: Strange workaround for slow query
Дата
Msg-id pupr3cqgwq.fsf@srv.protecting.net
обсуждение исходный текст
Ответ на Strange workaround for slow query  (sverhagen@wps-nl.com)
Список pgsql-performance
In article <OF6136AD9B.D40F3AF5-ONC12576E2.002D5763-C12576E2.002FBD70@imtechrelay.nl>,
sverhagen@wps-nl.com writes:
> SELECT * FROM events_events LEFT OUTER JOIN events_event_types ON eventType_id=
> events_event_types.id WHERE severity=70 AND (eventType_id IN (71)) ORDER BY
> datetime DESC LIMIT 50;
> Now I have at least two possibilities:
> - Implementing the dummy value as shown above in my source code to improve
> query performance (dirty but effective)
> - Further investigating what is going on, which at this point is something I
> need help with

First I'd change the query.  You build an OUTER JOIN and immediately
convert it to an INNER JOIN by referencing the "severity" column.

Then show us what EXPLAIN ANALYZE says to the problem.

В списке pgsql-performance по дате отправления:

Предыдущее
От: Tom Lane
Дата:
Сообщение: Re: Bad query plan inside EXISTS clause
Следующее
От: Benoit Delbosc
Дата:
Сообщение: Re: Bad query plan inside EXISTS clause