Kind of the million dollar question. People like to complain about cassandra, but that just brings up the adage about C++: people complain about the things they use.
But let's not pretend that cassandra isn't almost always a bear. The other problem is that cassandra keeps things up (and never gets the credit for it) but that creates a host of edge cases and management headaches (which makes management hate it).
Most competitors abandon AP for CP (HBase and Cockroach and I think FoundationDB) in order to get joins and SQL, but the BFD on cassandra is the AP design.
Scylla did a C++ rewrite to address tail latency due to JVM GC, but after an explosive release cycle, they basically stalled at partial 2.2 compatiblity. Rocksandra isn't in mainline and doesn't appear to be worked on anymore.
I follow the Jepsen tests a lot: they don't seem to have found a magic solution.
I think Cassandra stopped short of some key OSS deliverables, and I think they could simplify the management as well, both with a UI for admin and with some re-jiggering of how some things work on nodes. The devs are simply swamped with stability and features right now.
And Datastax won't help that much, what admin UI cassandra had was abandoned, and I half think the reason they acquired TLP was that TLP was producing/sponsoring useful admin tooling.
I would love to try something new. What appeals to me about cassandra is the fundamentals of the design, and the fair amount of tranparency there is (although there is still some marketing bullcrap that surrounds it like "CQL is like SQL" and other big lies).
So many other NoSQL's are bolt-on capabilities for handling distribution that Jepsen exposes (MongoDB famously) and have sooo much bullcrap in their claims. All the NoSQLs are desperate for market share, so they all lie about CAP and the edge cases.
Purely distributed databases are VERY HARD and are open to exaggeration, handwaving, and false demonstrations by the salesmen, but those people won't be around when you need a database like this to shine: when the shit hits the fan, you lose an entire datacenter, or similar things.
> Scylla did a C++ rewrite to address tail latency due to JVM GC, but after an explosive release cycle, they basically stalled at partial 2.2 compatiblity
Could you explain this more? Because Scylla has had pretty steady major release updates over the past few year. See the timeline of updates here:
We have long since passed C* 3.11 compatibility. In fact, if anything, Scylla, while maintaining a tremendous amount of Cassandra compatibility, now offers better implementations of features present in Cassandra (Materialized Views, Secondary Indexes, Change Data Capture, Lightweight Transactions), plus unique features of its own — incremental compaction and workload prioritization.
But if there's something in particular you're thinking of, I'm open to hear more on how you see it.
