Better checkpoint test

It would be good to have better checkpoint tests. Specifically to ensure that we are creating valid checkpoints in a reproducible way.

One way we could approach this problem would be to:

• Create several tables (three is a good number).
• Continually execute an identical insert into each of the tables protected by a single transaction.
• Occasionally checkpoint all three databases.
• Confirm that the checkpoints for all three of the tables contain identical data.