Re: Joel's Performance Issues WAS : Opteron vs Xeon

On Fri, Apr 22, 2005 at 05:04:19PM -0400, Joel Fradkin wrote:
> And is the system always going to be used by only one user?
> No we have 400+ concurrent users
>
> I guess the question is if this big select is representative of the load you
> expect in production.
> Yes we see many time on the two processor box running MSSQL large return
> sets using 100%cpu for 5-30 seconds.
>
> What happens if you execute the query more times? Do the times stay the
> same as the second run?
> I will definitely have to pressure testing prior to going live in
> production. I have not done concurrent tests as honestly single user tests
> are failing, so multiple user testing is not something I need yet.

I would very, very strongly encourage you to run multi-user tests before
deciding on mysql. Mysql is nowhere near as capable when it comes to
concurrent operations as PostgreSQL is. From what others have said, it
doesn't take many concurrent operations for it to just fall over. I
can't speak from experience because I avoid mysql like the plague,
though. :)

Likewise, MSSQL will probably look better single-user than it will
multi-user. Unless you're going to only access the database single-user,
it's just not a valid test case (and by the way, this is true no matter
what database you're looking at. Multiuser access is where you uncover
your real bottlenecks.)
--
Jim C. Nasby, Database Consultant decibel(at)decibel(dot)org
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