Обсуждение: Optimizer question with equivalent joins

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Optimizer question with equivalent joins

От
Dirk Lutzebaeck
Дата:
Hello,

say I have a join which says
   t.a = t.b and t.b = t.c

do I need to give the optimizer a hint by saying it more redundantly
   t.a = t.b and t.b = t.c and t.c = t.a

or is this just counter productive because there is one more join?

In the real world I have 10-20 equivalent joins which would really
blow up if I have to choose the second option.

Dirk




Re: Optimizer question with equivalent joins

От
Tom Lane
Дата:
Dirk Lutzebaeck <lutzeb@aeccom.com> writes:
> say I have a join which says
>     t.a = t.b and t.b = t.c
> do I need to give the optimizer a hint by saying it more redundantly
>     t.a = t.b and t.b = t.c and t.c = t.a

Not since about 7.0.3 ...
        regards, tom lane