Skip site navigation (1) Skip section navigation (2)

Re: Another optimizer question

From: Dennis Haney <davh(at)diku(dot)dk>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Another optimizer question
Date: 2004-01-27 19:08:58
Message-ID: 4016B74A.2010907@diku.dk (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:

>Dennis Haney <davh(at)diku(dot)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...

-- 
Dennis

In response to

Responses

pgsql-hackers by date

Next:From: Dave CramerDate: 2004-01-27 19:09:13
Subject: Re: index scan with functional indexes -- solved
Previous:From: Bruce MomjianDate: 2004-01-27 19:07:44
Subject: Re: Mixing threaded and non-threaded

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group