Re: SELECT with MANY tables

On Mon, 24 Nov 2003, Javier Carlos wrote:

> Quoting Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>:
>
> >
> > On Mon, 24 Nov 2003, Javier Carlos wrote:
> >
> > >
> > > Please enter a FULL description of your problem:
> > > -------------------------------------------------
> > > When I make a SELECT with many tables (more than 12), postgresql eats
> > all my
> > > %CPU and I've waited more than 1 hour and stays the same. The weird thing
> > is
> > > that with 10 tables the same select with the same joins only takes about 5
> > > seconds. First I thought that It was a problem related with one specific
> > table,
> > > but I've changed in the SELECT the tables and while the number of tables
> > remains
> > > less than 12 all is ok.
> >
> > As a question, does the query work if you SET geqo=off; or SET
> > geqo_threshold=<some higher number, say 20>?
> >
>
> I tried with setting geqo=off and It didn't work. Then I set
> geqo_threshold=20, and neither. In both the result was:
>
> server closed the connection unexpectedly
> This probably means the server terminated abnormally
> before or while processing the request.
> The connection to the server was lost. Attempting reset: Failed.

What does your postmaster log say? There should be something in there.
I also forgot to ask for EXPLAIN output under normal conditions and with
geqo off (although it's possible that it will fail as well for the latter)