Re: about explain analyze

On Fri, 28 Nov 2003, Tom Lane wrote:

> "Marc G. Fournier" <scrappy(at)postgresql(dot)org> writes:
> > did you happen to take a look at the other set of queries I sent you, that
> > were showing 39k and 41k explain results?
>
> You mean this one?

Yup ...

> > time psql -c "explain analyze select max(intag) from ndict3" 186_archives
> QUERY PLAN
> ----------------------------------------------------------------------------------------------------------------------------
> Aggregate (cost=40168.96..40168.96 rows=1 width=4) (actual time=48953.823..48953.827 rows=1 loops=1)
> -> Seq Scan on ndict3 (cost=0.00..34560.57 rows=2243357 width=4) (actual time=4.903..-666785.605 rows=3516680 loops=1)
> Total runtime: 48982.514 ms
> (3 rows)
>
> 0.000u 0.005s 0:49.06 0.0% 0+0k 0+0io 0pf+0w
> > time psql -c "select max(intag) from ndict3" 186_archives
> max
> ------------
> 2147418368
> (1 row)
>
> 0.000u 0.005s 0:03.06 0.0% 0+0k 0+0io 0pf+0w
>
> This looks like 46 seconds of overhead for 3516680 rows, or still right
> about 13 microseconds per row, so that's consistent. The negative
> "actual time" measurement for the Seq Scan row seems pretty broken
> though :-(.
>
> 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 :)

----
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Email: scrappy(at)hub(dot)org Yahoo!: yscrappy ICQ: 7615664