Re: postgreSQL query via JDBC in different OS taking different running time?

Aftab Ahmed Chandio <aftabac@siat.ac.cn> wrote:

> My query processes from JDBC (Java Program) to PostgreSQL. I use
> system time by invoking java function, I collect one time unit
> before the query statement perform and second after the execution
> of query statement.
> I found 85 ms time unit in DOS (win7) (laptop 4cores). both Java
> and PostgreSQL installed and invoked on the same machine,
> respectively.
> On the other hand, I use same process (separate installation) on
> linux on 8 cores physical machine with 2times greater then
> laptop.
> I found 150 ms. (which is a question for me because the time in
> Linux environment should give me half of the time taking on
> laptop)
> I also make same setting  of postgresql.conf in the linux setup,
> which is available same in the win7  setup, because win7 setup
> gives better performance of the query.
> What do u suggest me, where I need to make performance tuning?
> which configuration setting must need to modify in the linux?
> * laptop RAM 4 GB and Linux machine 32 GB

Given a little time, I could probably list 100 plausible reasons
that could be.  For my part, load balancing a production system
between PostgreSQL on Windows and on Linux hitting identical
databases on identical hardware, I saw 30% better performance on
Linux.

I would start by getting timings for query execution using EXPLAIN
ANALYZE, to see how PostgreSQL itself is performing on the two
environments.  I would test raw connect/disconnect speed.  I would
benchmark RAM using STREAM and disk using bonnie++.

You might want to review this page, and post a more detailed report
to the pgsql-performance list:

http://wiki.postgresql.org/wiki/SlowQueryQuestions

Posting to multiple lists is generally considered bad form.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company