Re: about explain analyze

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: about explain analyze
Date: 2003-11-28 20:19:43
Message-ID: 621.1070050783@sss.pgh.pa.us
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"Marc G. Fournier" <scrappy(at)postgresql(dot)org> writes:
> On Fri, 28 Nov 2003, Tom Lane wrote:
>> Now that I recall, didn't you complain of something similar with a beta?

> Yup ... and I bet its not reproducible yet again, is it? :) That would
> make for twice though, with v7.4, that I've come up with - results :)

Well, it's not reproducibly negative, but it seems reproducibly wrong:

Aggregate (cost=40168.96..40168.96 rows=1 width=4) (actual time=49641.603..49641.611 rows=1 loops=1)
-> Seq Scan on ndict3 (cost=0.00..34560.57 rows=2243357 width=4) (actual time=34.854..724754.474 rows=3570252 loops=1)
Total runtime: 49688.524 ms

Aggregate (cost=40168.96..40168.96 rows=1 width=4) (actual time=36625.013..36625.018 rows=1 loops=1)
-> Seq Scan on ndict3 (cost=0.00..34560.57 rows=2243357 width=4) (actual time=0.128..-676113.173 rows=3572298 loops=1)
Total runtime: 36625.779 ms

Aggregate (cost=40168.96..40168.96 rows=1 width=4) (actual time=41380.881..41380.885 rows=1 loops=1)
-> Seq Scan on ndict3 (cost=0.00..34560.57 rows=2243357 width=4) (actual time=0.091..718200.092 rows=3575264 loops=1)
Total runtime: 41381.504 ms
(3 rows)

I'm wondering if there's an actual bug in gettimeofday() in this
platform, such that once in a while it returns a value that's off
a minute or so ...

regards, tom lane

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