Because multi-master clustering is extremely hard to do when you need transactional semantics. For those that need it, scaling up is by far the easiest path. Most of us will never exceed the growth rate of server capacity over time, so you can just keep going up. HA using stand-bys and failover is well documented, and quite sufficient I might add.
If you don't need transactional semantics and you do need globally distributed multi-master key/value storage, I would not switch from Cassandra to PG, you already have a good solution for that.
If you don't need transactional semantics and you also do not need globally distributed multi-master key/value storage, use whatever you want, it doesn't really matter.
If you don't need transactional semantics and you do need globally distributed multi-master key/value storage, I would not switch from Cassandra to PG, you already have a good solution for that.
If you don't need transactional semantics and you also do not need globally distributed multi-master key/value storage, use whatever you want, it doesn't really matter.