I have three databases.

Database A in one plans in the city of Belo Horizonte
Database B in one plans in São Paulo's city
Database C in one plans in the city of Rio de Janeiro

As master database has the A, and in him,
I have the white schema that has 4 tables that are
all they have the column city in common.
I have to answer through snapshot the tables
for the database B, C with interval of 30 seconds.
And for the database that this in São Paulo's city
should only go the data of the tables that
owned to that city.
The same happening for the City Rio de Janeiro.

1) Do I have to create a schema in you plan them B,
identical C to the of the it plans A???
2) do I create the snap in the banks B,C or in the A???
3) it would not be better to create a dblink of the database
B,C and later to create Views for the database passing
IT @dbklink with the clause where city = ' São Paulo'
and tb where city = ' Rio of Janeiro'???
4) it is only enough to create the snapshot in it plans
it A?B?C with the dblink configured correctly
that the load is made surely???
5) does anybody have some example script so that I
can looks at????