maybe it can not directly upgrade from V7 to V9 with PostgreSQL
first step migration from V7 with Oracle to V9 with Oracle
second change DB from V9 with Oracle to V9 with PostgreSQL.
If you check the Upgrade Guide it should be able to help you, however you are on an unsupported version (v7) and BMC advise that you open a ticket with them in such situations. Also bear in mind that the PostgreSQL DB can be the one supplied by BMC or your own external PostgreSQL DB (the BMC supplied one has always worked well for me).
In older versions of Control-M you had to do a swap like this as part of the upgrade process (you couldn't change DB "brands" in an existing system) and maybe that is still the case. You should also consider using the Amigo process.