DATA LOADING

This section focuses on data loading. Many of the same techniques presented in the data extraction section apply here too, so the focus is on areas that have not been covered before.

Database Snapshots

Database snapshots were introduced as a way to persist the state of a database at a specific point in time. The underlying technology is referred to as copy-on-first-write, which is a fancy way of saying that once you create the database snapshot, it is relatively cheap to maintain because it only tracks things that have changed since the database snapshot was created. Once you have created a database snapshot, you can change the primary database in any way — for instance, changing rows, creating indexes, and dropping tables. If at any stage you want to revert all your changes back to when you created the database snapshot, you can do that very easily by doing a database restore using the database snapshot as the media source.