Re: Automatic optimization of IN clauses via INNER JOIN

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От Grzegorz Jaśkiewicz
Тема Re: Automatic optimization of IN clauses via INNER JOIN
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Msg-id 2f4958ff0912180724t58940a36q1770df3609b38f1d@mail.gmail.com
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Ответ на Re: Automatic optimization of IN clauses via INNER JOIN  (Robert Haas <robertmhaas@gmail.com>)
Ответы Re: Automatic optimization of IN clauses via INNER JOIN  (Robert Haas <robertmhaas@gmail.com>)
Список pgsql-performance
2009/12/18 Robert Haas <robertmhaas@gmail.com>:
> 2009/12/18 Grzegorz Jaśkiewicz <gryzman@gmail.com>:
>> On Fri, Dec 18, 2009 at 2:18 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>>
>>> NOT IN is the only that really kills you as far as optimization is
>>> concerned.  IN can be transformed to a join.  NOT IN forces a NOT
>>> (subplan)-type plan, which bites - hard.
>>
>> in a well designed database (read: not abusing NULLs) - it can be done
>> with joins too.
>
> But not by PostgreSQL, or so I believe.

using left join ?



--
GJ

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