One thing that's stopping us from switching over is that we need more real world success stories of other people making the switch and being better off. For all its warts, Cassandra is the devil we know, but ScyllaDB is definitely something we're keeping an eye on.
One suggestion that might make it easier for people to move over is thorough testing of mixed clusters. I wouldn't mind switching one node in my cluster over, if I could be certain it wouldn't screw up the entire cluster. I saw that they ran through the Jepsen tests and did a good job, it would be very interesting to see how a 50/50 cassandra/scylladb cluster would fare in the same tests!
Most people testing Scylla at this point are doing A/B testing, using some proxy to replicate the writes to both clusters and then comparing the two.
It's a shame though, because it makes it harder for medium-sized installations to convert. If you're running a small cluster, then getting a few more machines to test it out isn't that much of a burden. If you're so big that you have multiple clusters, you can probably roll through and upgrade cluster by cluster or keyspace by keyspace or something.
But between those two there's a medium size installation where an upgrade to ScyllaDB is a serious project that would eat up a sizeable chunk of the server budget just to test it out, and the ability to do a server-by-server upgrade of a running cluster would be invaluable.
On the other hand, that type of customer probably wouldn't be interested in premium support either, so there's probably little incentive for you to support that scenario over the large installation scenario. And that's totally fair, I might as well be wishing for unicorns and rainbows. :-)
On another note, DataStax recently announced that they'll be discontinuing the free version of OpsCenter from Cassandra 3.0 and forward. So you have a shot at grabbing people that are stuck on 2.x, because if there's a cost to upgrading anyway, and if you could offer something better than OpsCenter, your alternative might look very tempting indeed.
I really hope to try out Scylla with some of my cassandra schemas... see how much of the 10x -> 20x speed advantage really bears out.
I was suspicious of these guys originally but they've been pretty upfront with testing and despite the convenience of Java, I can see how they might get massive improvements in speed by doing lower-level C/C++ code.
We fully stand behind our claims, and don't want to be seen as the "oh, it's the vendor saying, of course it's good".
If you do happen to find an odd case in which we don't perform well, we'd love to hear about it and will work with you in fixing it.
There are more differences, like Aerospike holding all keys in memory, while Scylla does not have such limitation. I'm sure there are more differences in tunable consistency, HA and multi DC, but I'm not an Aerospike expert.
Also does Scylla support some sort of data locality as far as secondary index is concerned?
For example if I want to store comments, I'd want to store all comments that belong to the same forum thread in a single node. All these comments have the same thread_id. Then I can have a secondary index on thread_id. When I want to get all comments that belong to a certain thread I can just query on the thread_id secondary index and only 1 node is queried. Is that possible?
