ACID semantics subtley and indirectly requires locks. Any scenario where lock contention might be a problem would be a problem for an RDBMS (assuming the tradit

ACID semantics subtley and indirectly requires locks. Any scenario where lock contention might be a problem would be a problem for an RDBMS (assuming the traditional definition of RDBMS as a ACID compliant). Those scenarios can easily be “super-constant”, especially if you have to distribute across multiple nodes. That requires locks that are held for the duration of an “external call” over the network which is A Bad Idea and could definitely be “super-constant”.