We've had to build a system that does something like this. What we did was add a table that maintains versions. Then we had a master table, think of it as a book management system with versions of books. Every table in the system maintained two columns as part of the primary key, the version number and the book number. Any set of changes that came in were given a new number from the Version table, and the updates to the table or tables were stored with the new version. Then, when you query, you're either going for a specific version or the latest. If you're going for the latest, we get the latest version for that book, then only select the max version from each table where it is equal to or less than the version we're looking for. With the keys all clustered on these values the system is extremely fast and has scaled to millions & millions of rows with no issues. Writing the code is a bit of a pain, but CTEs can help.