Thanks for the comment! It’s a common misunderstanding that no-sql dbs can’t be used for this, but any would work. Dynamo dB have consistent reads and conditional inserts, which is sufficient to build an optimistic locking system that ensures no double spent money.
No problem. You should look into this more. Conditional expressions in DDB do not provide aggregate expressions and can only determinate on single attributes belonging to the same table.
Consistent reads aren’t enough.
You would need to prevent phantom reads. DDB doesn’t support range locking since it’s a LSMT. You can contact the AWS solutions engineers or perform a quick online search: ‘However, neither DynamoDB nor the library support locking for range queries, thus phantom reads can potentially result in phantom reads.’
