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.ja...@gmail.com> wrote: > On Thu, Jul 12, 2012 at 9:07 AM, Ants Aasma <a...@cybertec.at> wrote: > > On Thu, Jul 12, 2012 at 3:48 PM, Yan Chunlu <springri...@gmail.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 >
