Hi Vivek,
What is the advantage of postgres over derby ? We can use Derby but why we are using postgres ?
Quite a few Java projects including OfBiz make use of Derby as a database simply because it is written in Java and can therefore be set up to run 'out of the box' without requiring the user to install separate database drivers and database package. For new users this is ideal as they can quickly have a running demo system to play with without getting too bogged down in configuration issues.
For production however you may need something which is not only faster but more scalable and more robust and more secure. Production databases have the means to backup database tables while other users are still using them. Other facilities might include the ability to setup master/slave databases or support transaction based processing complete with commit and rollback. You will almost certainly also be able to restrict what actions OfBiz can perform on which tables in order to improve security.
Just some of the reasons why you might use postgres or MySQL instead of Derby ;-)
Regards, David Legg
