Java: versioned data structures?

Question

I have a data structure that is pretty simple (basically a structure containing some arrays and single values), but I need to record the history of the data structure so that I

Answer 1

How long will the application be running for?

It seems like you could do what you suggested -- playing the transactions back -- but cache the data structure and list of transactions at particular points in time (every hour or every day?) to ease the pain of having to go through O(n) operations every time you need to rebuild the collection from scratch.

Granted, there is definitely a trade-off between space (that the cache takes up) and the number of operations needed to re-build it, but hopefully you will be able to find a happy medium for it.