Financial ledgers that allow backdated entries create a critical problem: the same account balance query can return different results depending on when it's run. This inconsistency can cause serious legal and audit issues. The solution is versioned reads — each account carries an integer version that increments with every new entry, and entries store the account version at insertion time. This allows any historical balance to be reproduced exactly as it appeared at a given point in time, regardless of later backdated corrections. The post distinguishes between Recording ledgers (data consolidation, eventually consistent) and Authorizing ledgers (gatekeeping), noting that read versioning is essential for Recording ledgers once stakeholders depend on them to explain what the company knew at a specific moment.
