EXISTS vs IN vs OUTER JOINS

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От Tomasz Myrta
Тема EXISTS vs IN vs OUTER JOINS
Дата
Msg-id 3E019B71.5050901@klaster.net
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Ответы Re: EXISTS vs IN vs OUTER JOINS  ("Josh Berkus" <josh@agliodbs.com>)
Список pgsql-performance
Hi
Few days ago I read, that EXISTS is better than IN, but only if there
are many records (how many?). I was wondering which one is better and
when. Did anyone try to compare these queries doing the same work:

- select * from some_table t
     where t.id [not] in (select id from filter);
- select * from some_table t
     where [not] exists (select * from filter where id=t.id);
- select * from some_table t
    left join filter f using (id)
   where f.id is [not] null;

Regards,
Tomasz Myrta


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