Re: What happens between end of explain analyze and end of query execution ?

On Sat, Apr 6, 2013 at 9:27 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Franck Routier <franck(dot)routier(at)axege(dot)com> writes:
> > Le 05/04/2013 16:17, Tom Lane a écrit :
> >> What have you got the statistics targets set to in this database?
>
> > Ok, the problem definitely comes from the default_statistics_target
> > which is obviously too high on the database.
>
> Yeah, eqjoinsel() is O(N^2) in the lengths of the MCV lists, in the
> worst case where there's little overlap in the list memberships.
> The actual cost would depend a lot on the specific column datatypes.
>

I guess this pre-emptively answers a question I was intending to ask on
performance: Whether anyone increased default_statistics_target and came
to regret it. I had seen several problems fixed by increasing
default_statistics_target, but this is the first one I recall caused by
increasing it.

Do you think fixing the O(N^2) behavior would be a good to-do item?

Cheers,

Jeff