Re: Logical Aggregate Functions (eg ANY())

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От Robert James
Тема Re: Logical Aggregate Functions (eg ANY())
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Msg-id CAGYyBgie=9a3JaM9tYORVYhtwybW_Er+v+B+fY2Bof377xgkvQ@mail.gmail.com
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Ответ на Re: Logical Aggregate Functions (eg ANY())  (Marti Raudsepp <marti@juffo.org>)
Ответы Re: Logical Aggregate Functions (eg ANY())
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On 12/15/11, Marti Raudsepp <marti@juffo.org> wrote:
> On Thu, Dec 15, 2011 at 18:10, Robert James <srobertjames@gmail.com> wrote:
>> How do I do the equivalent of an ANY() or ALL() in PG Aggregate SQL?
>
> Note that in many cases, writing an EXISTS(SELECT ...) or NOT
> EXISTS(...) subquery is faster, since the planner can often optimize
> those to a single index access -- whereas an aggregate function would
> necessarily need to walk through and evaluate all potential rows.
>

Really? The planner can't tell that, for instance, BOOL_AND (false, *)
is automatically false?

(BTW Thanks for the great responses everyone! On this and other posts
on this list)

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