Re: [PERFORM] EXPLAIN ANALYZE on 8.2 - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [PERFORM] EXPLAIN ANALYZE on 8.2
Date
Msg-id 10651.1166503380@sss.pgh.pa.us
Whole thread Raw
In response to Re: [PERFORM] EXPLAIN ANALYZE on 8.2  ("Simon Riggs" <simon@2ndquadrant.com>)
List pgsql-hackers
"Simon Riggs" <simon@2ndquadrant.com> writes:
> On Fri, 2006-12-15 at 09:56 -0500, Tom Lane wrote:
>> The fundamental problem with it was the assumption that different
>> executions of a plan node will have the same timing.  That's not true,
>> in fact not even approximately true.

> It doesn't make sense to me to claim that the timing is so important
> that we cannot do without it, at the same time as saying it isn't even
> approximately true that is highly variable.

Huh?  What I said was that successive executions of the same plan node
may take considerably different amounts of time, and the proposed
sampling patch failed to handle that situation with acceptable accuracy.

            regards, tom lane

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