Re: Poor performance using CTE

On 2012-11-21 13:32:45 -0300, Claudio Freire wrote:
> On Wed, Nov 21, 2012 at 1:24 PM, Andres Freund <andres@2ndquadrant.com> wrote:
> > On 2012-11-21 13:16:25 -0300, Claudio Freire wrote:
> >> On Wed, Nov 21, 2012 at 12:32 PM, Andres Freund <andres@anarazel.de> wrote:
> >> > +1
> >> >
> >> > WITH foo AS (SELECT ...) (barrier=on|off)?
> >> >
> >> > 9.3 introduces the syntax, defaulting to on
> >> > 9.4 switches the default to off.
> >>
> >> Why syntax? What about a guc?
> >>
> >> collapse_cte_limit?
> >
> > Because there are very good reasons to want to current behaviour. A guc
> > is a global either/or so I don't see it helping much.
>
> set collapse_cte_limit=8;
> with blah as (blah) select blah;
>
> Not global at all.

Not very manageable though. And it doesn't help if you need both in a
query which isn't actually that unlikely.

Greetings,

Andres Freund

--
 Andres Freund                       http://www.2ndQuadrant.com/
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