ClickHouse is open source it's def not trash for olap and ts

clickhouse could barely complete a 15 min moving average; last time I checked it required a very slow correlated subquery. That's pretty much where I stopped evaluating it.

edit: after looking it up again, looks like that is still the case, and you have have to be fairly limited with cumulative aggregates if you want the keep performance. maybe someday, but as of now, still not very good.

We used ScyllaDB at my last employer to store time-series data, it worked quite well, though you do have to add a lot of supporting code, it doesn't come out-of-the-box for free.

ScyllaDB isn't really OLAP - it mostly just a glorified logger that throws stuff on disk. It is a terrible TSBD when you really need a TSDB - like basically all open source dbs. we're looking at timescale right now, but basically as the best of the worst. i have the budget no way i'd be using it.

We recommend running KairosDB on top of Scylla for TSDB use cases.