Question:
Are MasterSource/MasterFields like a filter in the sense
that the ClientDataSet retrieves all records and filters
for those records that match the linked fields?
Answer:
It really depends on how you have it set up. If you set
PacketRecords to -1 then yes, that is the way it works.
If you have PacketRecords to 0 and FetchOnDemand as True,
then it will use Provider.SetParams and fetch just the
records that match the master.