Postgresql with Hibernate issues

Hello:

I have a java application that starts several processes to retrieve data and
store them into the database tables;

When I run this on winXP and with Hibernate/Mysql, everything looks ok.

Now I need to use postgresql, so I change the hibernate configuration file.

When I run the program, the tables are created and records inserted into
several tables.

But the ID for each table are all wrong.

A closer look indicates that the hibernate is using the select nextval for
each insert command, which results in the

ID for each table is considered as a global one,

Tables ID

table1 1 , 5

table2 2,3,4

table3 6

table4 7,8

table1 9 ,10

Why this is happening, does this mean Hibernate with postgresql can not
work?, whileas same application+ Hibernate with mysql

Works perfectly fine?

Thanks a lot for your advices.

Shemy