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List:       postgresql-general
Subject:    Re: [HACKERS] sequential scan result order vs performance
From:       Corey Huinker <corey.huinker () gmail ! com>
Date:       2016-10-31 20:54:18
Message-ID: CADkLM=f43+ceZc0YYy_U+-7aDcbczuJrPp-L+k+bw7qgZNwd=g () mail ! gmail ! com
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On Sun, Oct 30, 2016 at 11:37 PM, Jim Nasby <Jim.Nasby@bluetreble.com>
wrote:

> BTW, I've sometimes wished for a mode where queries would silently have
> result ordering intentionally futzed, to eliminate any possibility of
> dependence on tuple ordering (as well as having sequences start at some
> random value). I guess with the hooks that are in place today it wouldn't
> be hard to stick a ORDER BY random() in if there wasn't already a Sort node
> at the top level...


+1
In Oracle, we sorta had that feature by adding a parallel hint to a query
even if it didn't need it. It came in handy.

[Attachment #3 (text/html)]

<div dir="ltr"><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Oct 30, \
2016 at 11:37 PM, Jim Nasby <span dir="ltr">&lt;<a \
href="mailto:Jim.Nasby@bluetreble.com" \
target="_blank">Jim.Nasby@bluetreble.com</a>&gt;</span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex">BTW, I&#39;ve sometimes wished for a mode where queries would \
silently have result ordering intentionally futzed, to eliminate any possibility of \
dependence on tuple ordering (as well as having sequences start at some random \
value). I guess with the hooks that are in place today it wouldn&#39;t be hard to \
stick a ORDER BY random() in if there wasn&#39;t already a Sort node at the top \
level...</blockquote></div><div class="gmail_extra"><br></div>+1<br>In Oracle, we \
sorta had that feature by adding a parallel hint to a query even if it didn&#39;t \
need it. It came in handy.</div></div>



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