From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Florian Pflug <fgp(at)phlo(dot)org> |
Cc: | Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Kevin Grittner <kgrittn(at)ymail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: [PATCH] Negative Transition Aggregate Functions (WIP) |
Date: | 2014-03-05 22:49:10 |
Message-ID: | 31886.1394059750@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Florian Pflug <fgp(at)phlo(dot)org> writes:
> On Mar5, 2014, at 18:37 , Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> My advice is to lose the EXPLAIN output entirely. If the authors of
>> the patch can't agree on what it means, what hope have everyday users
>> got of making sense of it?
> The question isn't what the current output means, but whether it's a
> good metric to report or not.
If you can't agree, then it isn't.
> If we don't report anything, then how would a user check whether a query
> is slow because of O(n^2) behaviour of a windowed aggregate, or because
> of some other reasons?
[ shrug... ] They can see whether the Window plan node is where the time
is going. It's not apparent to me that the extra numbers you propose to
report will edify anybody.
regards, tom lane
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