Re: not in(subselect) in 8.4
| От | Tom Lane |
|---|---|
| Тема | Re: not in(subselect) in 8.4 |
| Дата | |
| Msg-id | 8918.1235144033@sss.pgh.pa.us обсуждение исходный текст |
| Ответ на | not in(subselect) in 8.4 (Grzegorz Jaśkiewicz <gryzman@gmail.com>) |
| Ответы |
Re: not in(subselect) in 8.4
Re: not in(subselect) in 8.4 Re: not in(subselect) in 8.4 |
| Список | pgsql-performance |
=?UTF-8?Q?Grzegorz_Ja=C5=9Bkiewicz?= <gryzman@gmail.com> writes:
> I mean query like:
> select id from foo where id not in ( select id from bar);
> into:
> select f.id from foo f left join bar b on f.id=b.id where b.id is null;
Postgres does not do that, because they don't mean the same thing ---
the behavior for NULLs in bar.id is different.
8.4 does understand that NOT EXISTS is an antijoin, though.
regards, tom lane
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