If you can make changes to your architecture, you might want to look into partitioning the data. That makes it very easy to move data out of one database and into another. That's pretty much what it's designed to do. But, it has a number of caveats, the biggest being that you can ensure that retrieval of your data is always going to filter by the same structure that you use to partition the data. If you can't guarantee that, I wouldn't suggest this approach. Otherwise, it's a very viable method. This is an introductory article from Microsoft. There are other resources online to learn more.