Does every master entity row has a seperate RowSet object

Yes every master entity row has a seperate RowSet object containing all its child rows...

Let us take the Department and Employee tables...Assume that the primary key of the department table is the "DepartmentName" and not the "DepartmentId"... Let us say that there is an association between the Department entity and the Employee entity based on the "DepartmentId" attribute, so that the Department entity is the master and the Employee entity is the child..

So for every department row, there should be a RowSet using which all the associated Employee's can be found...

Even if there are two deparment rows having the same "DepartmentId" values, each row will have a seperate RowSet object...but both the RowSet objects will be pointing to the same iterator...

So if multiple master rows have the same source attribute value , then ADF bc is clever enough to fetch all the rows from the middle tier instead of firing queries to the database to fetch the child rows...

This is true even if the association accessors are retained.

Does this mean anything?

This information is given just to explain that ADFbc is good at deciding when it has to go to database and whether it can fetch all the necessary information from the middle tier