[pgr0ss]

> 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:

https://github.com/pgr0ss/pgledger/blob/df5541dcf25f416a6a24...

I have a mental TODO to add a query function to make this simpler.

[pgr0ss]

I updated the README and added an example test: https://github.com/pgr0ss/pgledger?tab=readme-ov-file#histor...

[accrual]

That makes sense and is an elegant solution. This way one can check the balance at any time without recalculating, but we still have an audit log to find discrepancies when the balance is expected to be zero but is not.