On Fri, 3 Oct 2003, Kathy Zhu wrote:
> Hi,
>
> I notices a weird thing here.
>
> version 7.2.1
> on Solaris
>
> table "test", has a field "state".
> There are 4 "state" values, 1, 2, 3, 4.
>
> select count(*) from test group by state;
> took 11500 msec
>
> but
>
> select count(*) from test where state = 1;
> select count(*) from test where state = 2;
> select count(*) from test where state = 3;
> select count(*) from test where state = 4;
> total took 626 msec
>
I believe Solaris's qsort implementation (which is used for the group by)
has problems dealing with large numbers of similar values.
I think in later versions of pg our own qsort is used.
Kris Jurka