> how do we efficiently get the balance of a certain account at a certain date time?
This depends on how you implement the ledger. For pgledger, I store the balance in every entry, so to find a historical balance, you just need to find the most recent entry before that time:
This depends on how you implement the ledger. For pgledger, I store the balance in every entry, so to find a historical balance, you just need to find the most recent entry before that time:
https://github.com/pgr0ss/pgledger/blob/df5541dcf25f416a6a24...
I have a mental TODO to add a query function to make this simpler.