Hi Lester,  I have definitely asked similar questions to the client.  But they have started to use this historical database for their own reporting, etc. and that isn't its original purpose.  Having said that, there is not an easy way to identify changes, but I may talk to them further about whether they can ask the provider to only give them the delta of changes from previous data cuts.  It would certainly be much easier if I only had to deal with a smaller amount of data to add/update to the existing content.