suggestion

[Knevil]

think about using MongoDB instead of PostgresDB in possible future pool upgrade, MongoDB is much lighter weight on the servers and more scalable

[equ1miner]

FYI You can run your stratums utilizing the built-in ZMQ message bus and to commit user share weights to the database externally to improve performance.
Pruning your db will also drop its size considerable.

Redis is actually a better canidate but would require a quite the re-write of many jobs. BTW Oliver has communicated he doesn't plan to add any other persistance models in the future.