Re: PostgreSQL vs. MySQL

...and on Sat, Jul 05, 2003 at 12:24:18AM +0200, Bjoern Metzdorf used the keyboard:
> >> Afaik, your original posting said postgresql was 3 times slower than
> >> mysql and that you are going to leave this list now. This implied
> >> that you have made your decision between postgresql and mysql,
> >> taking mysql because it is faster.
> >
> > Well, that shows what you get for making implications.  The client is
> > sticking with postgres and we are coding around the issue in other
> > ways.
>
> As many other guys here pointed out, there are numerous ways to tune
> postgresql for maximum performance. If you are willing to share more
> information about your particular project, we might be able to help you out
> and optimize your application, without the need to code around the issue as
> much as you may be doing right now.
> Even if it is not possible for you to share enough information, there are a
> lot of places where you can read about performance tuning (if not in the
> docs then in the archives).
>

Also, I should think the clients would not be too offended if Brian posted
some hint about the actual quantity of data involved here, both the total
expected database size and some info about the estimated "working set" size,
such as a sum of sizes of tables most commonly used in JOIN queries and the
percentage of data being shuffled around in those. Are indexes big? Are
there any multicolumn indexes in use? Lots of sorting expected? Lots of
UPDATEs/INSERTs/DELETEs?

Also, it would be helpful to know just how normalized the database is, to
provide some advice about possible query optimization, which could again
prove helpful in speeding the machinery up.

Another useful piece of information would be the amount of memory consumed
by other applications vs. the amount of memory reserved by the OS for cache,
and the nature of those other applications running - are they big cache
consumers, such as Apache with static content and a large load would be,
or do they keep a low profile?

I think this would, in combination with the information already posted, such
as the amount of memory and I/O subsystem info, at least enable us to advise
about the recommended shared_buffers, effective_cache_size, sort_mem,
vacuum_mem, and others, without compromising the intellectual property of
Brian's clients.

> > over and out.

I CC'd this post over to you, Brian, 'cause this signoff made me rather
unsure as to whether or not you're still on the list. Hope you don't mind.

Sincerely,
--
    Grega Bremec
    System Administration & Development Support
    grega.bremec-at-noviforum.si
    http://najdi.si/
    http://www.noviforum.si/