we've had great success building modular database stuff on top of leveldb with node, but as I have learnt more about databases it's become apparent to me that the idea of a modular database would be better implemented at a slightly lower level.
Level db provides a sorted key:value store, which, because of the sorted property, many things can be implemented on top of. For example, for replication, or for consistent materialized views, we often need a write ahead log. This can easily be implemented via a batch write to level, and writing the log into a section of the leveldb key space which is treated as append only.
