Re: Review remove {join, from}_collapse_limit, add enable_join_ordering

From: Andres Freund <andres(at)anarazel(dot)de>
To: pgsql-hackers(at)postgresql(dot)org
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Subject: Re: Review remove {join, from}_collapse_limit, add enable_join_ordering
Date: 2009-07-16 16:30:16
Message-ID: 200907161830.16898.andres@anarazel.de
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On Thursday 16 July 2009 18:23:06 Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On Thursday 16 July 2009 17:16:31 Tom Lane wrote:
> >> I tried the example query and couldn't get "Failed to make a valid plan"
> >> out of it ... what settings do you need for that?
> >
> > It unfortunately depends on settings and luck. This dependence on luck
> > was the reason why I liked geqo to behave "somewhat" deterministically...
> >
> > With {join,from}_collapse_limit = 100 it seems to be triggered reliably.
> > With lower values it seems harder trigger, with bigger it simply takes
> > too long to even get there.
>
> OK, I see it at 100. Would you confirm that what you get is the failure
> in random_init_pool (geqo_pool.c) not the identically-phrased message
> elsewhere? (If you have VERBOSITY = verbose you should see the error
> location info.)
Yes. I should have seen that. Its not exactly surprising...

Andres

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