Re: PostgreSQL scalability on Sun UltraSparc T1

On 29-7-2006 17:02, Jochem van Dieten wrote:
> Tweakers.net has done a database performance test between a Sun T2000 (8
> core T1) and a Sun X4200 (2 dual core Opteron 280). The database
> benchmark is developed inhouse and represents the average query pattern
> from their website. It is MySQL centric because Tweakers.net runs on
> MySQL, but Arjen van der Meijden has ported it to PostgreSQL and has
> done basic optimizations like adding indexes.

There were a few minor datatype changes (like enum('Y', 'N') to boolean,
but on the other hand also 'int unsigned' to 'bigint'), a few small
query changes (i.e. rewriting join orders, most turned out to be
necessary for mysql 5.0 and 5.1 as well anyway) and even fewer larger
query changes (including a subquery, instead of the results of another
query).

The indexes also included adding partial indexes and several combined
indexes.

All in all I think it took about a week to do the conversion and test
the specific queries. Luckily PostgreSQL allows for much clearer
information on what a specific query is doing and much faster
adding/removing of indexes (mysql rewrites the entire table).

> Arjen wrote about some of the preliminary results previously in
> http://archives.postgresql.org/pgsql-performance/2006-06/msg00358.php
> but the article has now been published http://tweakers.net/reviews/633/7
> This is all the more impressive if you scroll down and look at the
> behaviour of MySQL (after tweaking by both MySQL AB and Sun).

Actually, we haven't had contact with MySQL AB. But as far as I know,
the Sun engineers have contacted them about this.
As it turns out there are some suboptimal machine codes generated from
MySQL's source for the Niagara T1 and MySQL has some issues with
InnoDB's scaling in the later 5.0-versions:
http://www.mysqlperformanceblog.com/2006/07/28/returning-to-innodb-scalability/

Then again, we weren't able to compile the PG8.2 dev using all
optimizations of Sun's Studio Compiler (the mlibopt-switch failed), so
there is very likely more room for improvement on that field as well.

Best regards,

Arjen