Re: hash aggregation

On Wed, Oct 10, 2012 at 9:09 AM, Korisk <Korisk(at)yandex(dot)ru> wrote:
> Hello! Is it possible to speed up the plan?
> Sort (cost=573977.88..573978.38 rows=200 width=32) (actual time=10351.280..10351.551 rows=4000 loops=1)
> Output: name, (count(name))
> Sort Key: hashcheck.name
> Sort Method: quicksort Memory: 315kB
> -> HashAggregate (cost=573968.24..573970.24 rows=200 width=32) (actual time=10340.507..10341.288 rows=4000 loops=1)
> Output: name, count(name)
> -> Seq Scan on public.hashcheck (cost=0.00..447669.16 rows=25259816 width=32) (actual time=0.019..2798.058 rows=25259817 loops=1)
> Output: id, name, value
> Total runtime: 10351.989 ms

AFAIU there are no query optimization solution for this.

It may be worth to create a table hashcheck_stat (name, cnt) and
increment/decrement the cnt values with triggers if you need to get
counts fast.

--
Sergey Konoplev

a database and software architect
http://www.linkedin.com/in/grayhemp

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