On Sunday 08 June 2008 19:07:21 Gregory Stark wrote:
> "Joshua D. Drake" <jd@commandprompt.com> writes:
> > On Fri, 2008-06-06 at 20:19 -0400, Tom Lane wrote:
> >> Robert Treat <xzilla@users.sourceforge.net> writes:
> >>
> >> Actually, the reason it's still 10 is that the effort expended to get it
> >> changed has been *ZERO*. I keep asking for someone to make some
> >> measurements, do some benchmarking, anything to make a plausible case
> >> for a specific higher value as being a reasonable place to set it.
> >>
> >> The silence has been deafening.
> >
> > Not surprising really. It is a simple adjustment to make and it also is
> > easy to spot when its a problem. However it is not trivial to test for
> > (in terms of time and effort). I know 10 is wrong and so do you. If you
> > don't I am curious why I see so many posts from you saying, "Your
> > estimates are off, what is your default_statistics_target?" with yet
> > even more responses saying, "Uhh 10."
>
> Ah, but we only ever hear about the cases where it's wrong of course. In
> other words even if we raised it to some optimal value we would still have
> precisely the same experience of seeing only posts on list about it being
> insufficient.
>
The slipside to this is that we're not trying to find the perfect setting,
we're just trying to determine a number that will cause more benefit than
harm compared to the number we have now. While I am sure there are cases
where 100 is too low as well, I cannot recall ever having seen someone
suggest lowering the default_stats_target to something less than 100. (I
know sit back and wait for someone to comb the archives, just to find that 1
time).
--
Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL
