Re: *very* inefficient choice made by the planner (regarding

От: Jean-Luc Lachance
Тема: Re: *very* inefficient choice made by the planner (regarding
Дата: ,
Msg-id: 40C892BA.8080704@sympatico.ca
(см: обсуждение, исходный текст)
Ответ на: Re: *very* inefficient choice made by the planner (regarding  (Tom Lane)
Ответы: Re: *very* inefficient choice made by the planner (regarding  (Stephan Szabo)
Список: pgsql-performance

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*very* inefficient choice made by the planner (regarding IN(...))  (Frank van Vugt, )
 Re: *very* inefficient choice made by the planner (regarding  (Stephan Szabo, )
 Re: *very* inefficient choice made by the planner (regarding IN(...))  (Tom Lane, )
  Re: *very* inefficient choice made by the planner (regarding IN(...))  (Frank van Vugt, )
 Re: *very* inefficient choice made by the planner (regarding  (Jean-Luc Lachance, )
  Re: *very* inefficient choice made by the planner (regarding  (Tom Lane, )
   Re: *very* inefficient choice made by the planner (regarding  (Jean-Luc Lachance, )
    Re: *very* inefficient choice made by the planner (regarding  (Stephan Szabo, )
     Re: *very* inefficient choice made by the planner (regarding  (Stephan Szabo, )
 Re: *very* inefficient choice made by the planner (regarding  (SZUCS Gábor, )
  Re: *very* inefficient choice made by the planner (regarding  (Tom Lane, )
  Re: *very* inefficient choice made by the planner (regarding  (Stephan Szabo, )

I agree, but it should be a simple rewrite. No?

x IS NULL/IS NOT NULL AND/OR NOT EXISTS


Tom Lane wrote:

> Jean-Luc Lachance <> writes:
>
>>If the two statments are functionally equivalent, why can't PG rewrite
>>the "NOT IN" version into the more efficient "NOT EXISTS"?
>
>
> They're not equivalent.  In particular, the behavior in the presence of
> NULLs is quite different.
>
>             regards, tom lane
>



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