Re: That EXPLAIN ANALYZE patch still needs work - Mailing list pgsql-hackers

From Tom Lane
Subject Re: That EXPLAIN ANALYZE patch still needs work
Date
Msg-id 17316.1149713787@sss.pgh.pa.us
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In response to Re: That EXPLAIN ANALYZE patch still needs work  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: That EXPLAIN ANALYZE patch still needs work  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
Simon Riggs <simon@2ndquadrant.com> writes:
> On Wed, 2006-06-07 at 15:32 -0400, Tom Lane wrote:
>> I propose we revert this patch and think about an interrupt-driven
>> sampling method instead.

> I don't have much more faith in crazy scheme No.2 either. (Mine or
> yours...)

> Can we just have an option to avoid the timing altogether, please? I
> don't want to have long discussions about instrumentation, I just want a
> reasonably useful EXPLAIN ANALYZE in a reasonable amount of time - one
> that we never, ever have to doubt whether the sampling works correctly
> on a Miasmic-367 with HyperKooling.

Frankly, I think the pre-existing version of EXPLAIN ANALYZE is fine.
People have been hyperventilating about the timing overhead but I think
that it's perfectly acceptable as-is.  Certainly the removal of timing
is not going to convert an intolerable EXPLAIN ANALYZE runtime into an
acceptable one; what it *is* likely to do is let you be misled about
which part of the query is the problem.
        regards, tom lane


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