Re: how could select id=xx so slow?

got it, thanks! without your help I really have no idea what should be fast
and what supposed to be slower.

I also find "select" involves a lot of writes:

iotop shows:

2789 be/4 postgres 0.00 B 57.34 M 0.00 % 0.00 % postgres: goov
conta 192.168.1.129(27300) SELECT

I knew that select could cause writes, but not at this magnitude....

On Fri, Jul 13, 2012 at 2:53 AM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> On Thu, Jul 12, 2012 at 9:07 AM, Ants Aasma <ants(at)cybertec(dot)at> wrote:
> > On Thu, Jul 12, 2012 at 3:48 PM, Yan Chunlu <springrider(at)gmail(dot)com>
> wrote:
> >> yes the system seems overloaded, I am dealing with a simple "INSERT"
> but not
> >> sure if it is normal that it took more time than the explain estimated:
> >
> > The estimated cost is in arbitrary units, its purpose is to compare
> > different execution plans, not estimate time taken. So it's completely
> > normal that it doesn't match actual time taken.
>
> Right. And to make explicit what you implied, when there is only one
> to do something (like insert a row, or do maintenance on an index) it
> often doesn't even attempt to cost that at all as there is no choice.
> So it is not just a matter of units.
>
> Cheers,
>
> Jeff
>