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

От: Tom Lane
Тема: Re: *very* inefficient choice made by the planner (regarding
Дата: ,
Msg-id: 25304.1086883145@sss.pgh.pa.us
(см: обсуждение, исходный текст)
Ответ на: Re: *very* inefficient choice made by the planner (regarding  (Jean-Luc Lachance)
Ответы: Re: *very* inefficient choice made by the planner (regarding  (Jean-Luc Lachance)
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, )

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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От: Stephan Szabo
Дата:
Сообщение: Re: *very* inefficient choice made by the planner (regarding
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