Re: Another optimizer question - Mailing list pgsql-hackers

From Dennis Haney
Subject Re: Another optimizer question
Date
Msg-id 4016B74A.2010907@diku.dk
Whole thread Raw
In response to Re: Another optimizer question  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Another optimizer question  (Hannu Krosing <hannu@tm.ee>)
List pgsql-hackers
Tom Lane wrote: <blockquote cite="mid24882.1075226771@sss.pgh.pa.us" type="cite"><pre wrap="">Dennis Haney <a
class="moz-txt-link-rfc2396E"href="mailto:davh@diku.dk"><davh@diku.dk></a> writes: </pre><blockquote
type="cite"><prewrap="">There is no constraint on the order of 'a', so why is pull_up_subqueries 
 
explicitly ignoring subqueries that contain an 'order by'?   </pre></blockquote><pre wrap="">
Because there would be no place to apply the sort operation. </pre></blockquote> Then why spend time doing it at all?
<blockquotecite="mid24882.1075226771@sss.pgh.pa.us" type="cite"><pre wrap=""> If you are saying you don't want the sort
tooccur, </pre></blockquote> I'm saying the sort makes no sense. So why even bother executing it?<br /><br
/><blockquotetype="cite"><pre wrap=""> why did you write it?</pre></blockquote> I believe the most common scenario
wouldbe that the subquery was expanded from a view...<br /><br /><pre class="moz-signature" cols="72">-- 
 
Dennis
</pre>

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