Postgres for the database for the start and maybe this does suffice. Maybe think now how you could model a transaction with something like Cassandra. Only appen

Postgres for the database for the start and maybe this does suffice. Maybe think now how you could model a transaction with something like Cassandra. Only append the data. No updates to transactions. The balance is the sum over all transactions over time. Use something like a double entry bookkeeping system so you don’t make up any money out of thin air. Keep in mind how to do reconciliation, what is a transaction, how to do idempotency. For the backend Erlang/BEAM.