They may be obvious to you, but you'd be surprised at how many people out there are doing stuff without optimistic concurrency control, locking or transactions.

They may be obvious to you, but you'd be surprised at how many people out there are doing stuff without optimistic concurrency control, locking or transactions. I mean Mongo only added transactions for updating multiple documents relatively recently. Plus from what I remember they originally missed out the "D" due to only writing to disk intermittently.