CockroachDB employee here - Yes, CockroachDB is a completely different database from PostgreSQL. CockroachDB supports HA from the bottom up with data broken up into ranges that are consistently replicated using Raft. As mentioned earlier in the thread, it uses the PostgreSQL wire protocol and supports a good amount of SQL (but not all since the dialect is quite large if you include extensions). If you are looking for HA with SQL compatibility, it would be worth taking a look at CockroachDB.