Re: count with high allocation - Mailing list pgsql-general

From Pavel Stehule
Subject Re: count with high allocation
Date
Msg-id j2v162867791004070726g8735509s1af1eb0a31d21af2@mail.gmail.com
Whole thread Raw
In response to count with high allocation  (paulo matadr <saddoness@yahoo.com.br>)
List pgsql-general
Hello

2010/4/7 paulo matadr <saddoness@yahoo.com.br>:
> Hi all,
> Monitoring "top" in database server  , i could  noticed an query with
> reserved  8GB on physical memory.
>
> select count(field) from big_table  1 inner join big_table2...
>
> There is the possibility of using another function with less memory
> allocation?
> Is there a way to limit the memory usage of the count?

probably you have unactualised statistic. What is result of EXPLAIN
ANALYZE select count(... ?

I think, so planner uses hash arrays

try to

set enable_hashagg to off;
and again SELECT ...

Regards
Pavel Stehule

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