backup and restore

Hello,

I have two databases db1 and db2 with the same database structure on
different systems with no network connection. In the first system with the
db1 database user updates the master data. At the end of every day, the user
needs to take the backup of updated data of master tables on db1 and update
the data on another system with db2 database.

We can't use WAL as in this as we want to take incremental backup of few
tables only and can't use slony as there is no network connection between
the systems.

Please suggest some solution.

Thanks,
Jyoti