On Fri, 2007-11-02 at 14:45 -0700, Joshua D. Drake wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On Fri, 02 Nov 2007 13:49:27 -0700
> "Jeffrey W. Baker" <jwbaker@acm.org> wrote:
>
> > Nested Loop Left Join (cost=13920.16..2257575559347.46
> > rows=3691992705807 width=128)
> >
> > After a call to ANALYZE, the same query gave me:
> >
> > Merge Left Join (cost=16382.02..16853.87 rows=126768 width=59)
> >
> > And runs in 5 seconds. If I had been able to tell pg to reject any
> > plan with cost over, say 10E9, that would have saved my server from
> > half an hour of nested sequential scans.
>
> I am confused as to why you would want to do that... seems like a
> band aid for lack of maintenance.
Well it's not "maintenance" really since all the inputs are temp tables,
but I do see your point.
Often I have wished for a language which is not SQL which would allow me
to simply specify the whole execution plan. That would cut out a lot of
ambiguity.
Pie in the sky, I know.
-jwb