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

He is running RHAS4, which is the latest 2.6.x kernel from RH. I believe
it should have done away with the RHAS3.0 Update 3 IO issue.

anjan

-----Original Message-----
From: Josh Berkus [mailto:josh@agliodbs.com]
Sent: Wednesday, April 20, 2005 4:23 PM
To: Joel Fradkin
Cc: pgsql-performance@postgresql.org
Subject: Re: [PERFORM] Joel's Performance Issues WAS : Opteron vs Xeon

Joel,

> I have MSSQL running on a 2 proc dell which until my load has
increased
> (over aprx 2 years) it was just fine. I totally agree that there are
better
> solutions based on this lists comments, but I have all Dell hardware
now
> and resist trying different vendors just to suit Postgres. I was under
the
> impression there were still issues with 64bit postgres and Linux (or
at
> least were when I purchased). I believed I could make my next
aquistion a
> opteron based hardware.

Yeah, sorry, the Dell stuff is a sore point with me.   You can't imagine
the
number of conversations I have that go like this:
"We're having a severe performance problem with PostgreSQL"
"What hardware/OS are you using?"
"Dell *650 with RHAS 3.0 ...."

BTW, which Update version is your RHAS?   If you're on Update3, you can
grab
more performance right there by upgrading to Update4.

> Again I am not at all trying to critasize any one, so please except my
> apology if I some how came across with that attitude. I am very
> disappointed at this point. My views may not be that great (although I
am
> not saying that either), but they run ok on MSSQL and appear to run ok
on
> MYSQL.

Yeah.  I think you'll find a few things that are vice-versa.   For that
matter, I can point to a number of queries we run better than Oracle,
and a
number we don't.

Your particular query problem seems to stem from some bad estimates.
Can you
post an EXPLAIN ANALYZE based on all the advice people have given you so
far?

> I wish I did understand what I am doing wrong because I do not wish to
> revisit engineering our application for MYSQL.

I can imagine.

> I would of spent more $ with Command, but he does need my data base to
help
> me and I am not able to do that.

Yes.  For that matter, it'll take longer to troubleshoot on this list
because
of your security concerns.

> I agree testing the whole app is the only way to see and unfortunately
it
> is a time consuming bit. I do not have to spend 4k on MYSQL, that is
if I
> want to have their premium support. I can spend $250.00 a server for
the
> commercial license if I find the whole app does run well. I just
loaded the
> data last night and only had time to convert one view this morning. I
am
> sure it is something I do not understand and not a problem with
postgres. I
> also am willing to take time to get more knowledgeable, but my time is
> running out and I feel honestly stupid.

You're not.  You have a real query problem and it will require further
troubleshooting to solve.  Some of us make a pretty handsome living
solving
these kinds of problems, it take a lot of expert knowledge.

> It was never my intention to make you feel like I was flaming anyone
> involved. On the contrary, I feel many have taken time to look at my
> questions and given excellent advice. I know I check the archives so
> hopefully that time will help others after me.

Well, I overreacted too.   Sorry!

> I may find that revisiting the datasets is a way to make PG work, or
as you
> mentioned maybe I can get some one with more knowledge to step in
locally.
> I did ask Tom if he knew of anyone, maybe some one else on the list is
> aware of a professional in the Tampa FL area.

Well, Robert Treat is in Florida but I'm pretty sure he's busy
full-time.

> Realistically I don't think a 30k$ Dell is a something that needs to
be
> junked. I am pretty sure if I got MSSQL running on it, it would
outperform
> my two proc box. I can agree it may not have been the optimal
platform. My
> decision is not based solely on the performance on the 4 proc box.

Oh, certainly it's too late to buy a Sunfire or eServer instead.   You
just
could have gotten far more bang for the buck with some expert advice,
that's
all.   But don't bother with Dell support any further, they don't really
have
the knowledge to help you.

So ... new EXPLAIN ANALYZE ?

--

--Josh

Josh Berkus
Aglio Database Solutions
San Francisco

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TIP 8: explain analyze is your friend