Poor performance in Porting Oracle based application to PostgreSQL

Hi all,

We are facing a performance degradation when we ported a Weblogic 6.0 sp2 (using
BMP entity EJBs) from Oracle 8.1.7 to PostgreSQL 7.1.3 both using Linux RedHat.
One of most insert/update intensive tasks is taking double the time it took in
Oracle.

Did anyone have this problem before? What are your experiences in porting an BMP
EJB based application from Oracle to PostgreSQL? Is this just a problem of
tuning or it is inherent to PostgreSQL? Can a well-tuned PostgreSQL be that
slower than Oracle?

Thanks for your attention,

Roberto