Re: Feature Request --- was: PostgreSQL Performance Tuning

On Fri, May 04, 2007 at 12:33:29AM -0400, Greg Smith wrote:
>-bash-3.00$ psql
>postgres=# \timing
>Timing is on.
>postgres=# select count(*) from generate_series(1,100000,1);
> count
>--------
> 100000
>(1 row)
>
>Time: 106.535 ms
>
>There you go, a completely cross-platform answer. You should run the
>statement twice and only use the second result for better consistancy. I
>ran this on all the sytems I was around today and got these results:
>
>P4 2.4GHz 107ms
>Xeon 3GHz 100ms
>Opteron 275 65ms
>Athlon X2 4600 61ms

PIII 1GHz 265ms
Opteron 250 39ms

something seems inconsistent here.

>For comparison sake, these numbers are more useful at predicting actual
>application performance than Linux's bogomips number, which completely
>reverses the relative performance of the Intel vs. AMD chips in this set
>from the reality of how well they run Postgres.

You misunderstand the purpose of bogomips; they have no absolute
meaning, and a comparison between different type of cpus is not
possible.

>While I'm ranting here, I should mention that I also sigh every time I see
>people suggest we should ask the user how big their database is. The kind
>of newbie user people keep talking about helping has *no idea whatsoever*
>how big the data actually is after it gets into the database and all the
>indexes are built.

100% agreed.

Mike Stone