Re: SLOW query with aggregates

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От Tom Lane
Тема Re: SLOW query with aggregates
Дата
Msg-id 28366.1080073928@sss.pgh.pa.us
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Ответ на SLOW query with aggregates  ("A Palmblad" <adampalmblad@yahoo.ca>)
Список pgsql-performance
"A Palmblad" <adampalmblad@yahoo.ca> writes:
>  GroupAggregate  (cost=0.00..338300.34 rows=884 width=345) (actual
> time=86943.272..382718.104 rows=3117 loops=1)
>    ->  Merge Join  (cost=0.00..93642.52 rows=1135610 width=345) (actual
> time=0.148..24006.748 rows=1120974 loops=1)

You do not have a planning problem here, and trying to change the plan
is a waste of time.  The slowness is in the actual computation of the
aggregate functions; ergo the only way to speed it up is to change what
you're computing.  What aggregates are you computing exactly, and over
what datatypes?

            regards, tom lane

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