[mrtracy]

I think that the SQL-on-top, and optimistic model, are definitely things that can have a workflow-dependent performance impact and are relevant.

All databases do suffer under some red line of write contention; but optimistic databases will suffer more, and will start degrading at a lower level of contention. “Avoiding contention” is database optimization table stakes, and you should be structuring every schema you can to do so; but hot keys are almost inevitable when a certain class of real-time product scales, and they will show up in ways you do not expect. When it happens, you’d like your DBMS to give as much runway as possible before you have to make the tough changes to break through.

SQL-on-top becomes an issue for geographic distribution; without “pushing down” predicates, read-modify-write workloads, table joins, etc. on the client can incur significant round-trip time issuing queries. I think the lack of this is always going to present a persistent disadvantage vs selecting a competitor.

And again, given FDBs multiple-full-secondary model, it’s only a problem when working in real time, slower queries can work off a local secondary. But latest-data-latency is relevant for many applications.