Re: Some belated patch review for "Buffers" explain analyze patch

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: Greg Stark <stark(at)mit(dot)edu>, "<pgsql-hackers(at)postgresql(dot)org>" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Some belated patch review for "Buffers" explain analyze patch
Date: 2010-02-09 21:54:44
Message-ID: 603c8f071002091354pc79b125t35ad2ef5e505a710@mail.gmail.com
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On Tue, Feb 9, 2010 at 3:26 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> On 2/9/10 11:50 AM, Greg Stark wrote:
>> Secondly, I think it's printing the total buffer usage for that node
>> across the whole query -- not the average per iteration. I agree that
>> the average is probably more confusing but it's what we do for every
>> other stat. Do we want to be consistent? Call out the inconsistency
>> somehow, perhaps by tagging it "Total Buffer Usage:" or something like
>> that?
>
> I'd prefer to have the average; it's very confusing to have an explain
> row which has the cost per iteration, but the buffer usage per node.

The cost per iteration thing is IMO one of the most confusing parts of
the EXPLAIN output; I'm not really eager to see us replicate that
elsewhere.

...Robert

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