Re: Another optimizer question - Mailing list pgsql-hackers

From Hannu Krosing
Subject Re: Another optimizer question
Date
Msg-id 1075238534.2554.22.camel@fuji.krosing.net
Whole thread Raw
In response to Re: Another optimizer question  (Dennis Haney <davh@diku.dk>)
Responses Re: Another optimizer question  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Dennis Haney kirjutas T, 27.01.2004 kell 21:08:
> Tom Lane wrote: 
> > Dennis Haney <davh@diku.dk> writes:
> >   
> > > There is no constraint on the order of 'a', so why is pull_up_subqueries 
> > > explicitly ignoring subqueries that contain an 'order by'?
> > >     
> > Because there would be no place to apply the sort operation. 
> Then why spend time doing it at all? 
> >  If you are saying you don't want the sort to occur,
> >   
> I'm saying the sort makes no sense. So why even bother executing it?
> 
> >  why did you write it?
> I believe the most common scenario would be that the subquery was
> expanded from a view...

And why is it written on the outer level of view. AFAIK any select from
that view is also free to ignore it.

-----------
Hannu



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