We first started evaluating time series databases a month or two ago, some features like continuous aggregation (rollups) were enterprise only. Perhaps their strategy is to drive adoption and letting people try their feature out, hoping that some of these adoptors will end up using their managed solution. I checked their pricing, and the delta between their pricing and the underlying AWS instance seems quite reasonable.
We ended up testing Influx first, because it seems to be a safe choice with wider adoption and extensive documentation.
With Influx, it was very easy to put together a prototype quickly. But once we started throwing some real workload at it, it would lose writes under load. But it makes sense that it failed, because according to Influx's documentation (https://docs.influxdata.com/influxdb/v1.8/guides/hardware_si...), we would need cluster to make it work. Influx is very transparent in their documentation that writes and queries will fail immediately when a server is unavailable without cluster.
This isn't to say that Influx wouldn't work for other use cases. But at least in our use case, their open source offering isn't suitable for us, and it's unclear how much better the cluster version is.
Timescale, on the other hand, was able to handle the same workload under stress. As we are unable to backfill some of the ingressing data, it's quite vital that the system can degrade more gracefully.
For my use case, one feature that still need some work in Timescale is their real time aggregation. It is currently impossible to define a rollup on top of another rollup, which means that if you are ingesting a lot of data into the raw table, and you down sample into a wide time bucket (e.g. a day, or week), queries against these wider buckets will potentially ended up having to query a lot of data points, slowing the system down considerably. Granted, it is a new feature that just got released about a month ago. Hopefully, with multi-node nearing completion, continuous aggregation will get a bit more love.
I spoke with their engineers about this over Slack, and their suggestion was to manually modify the rollup materialized view to aggregate over a combination of the materialized buckets (currently handled by the continuous aggregation) + real time aggregation from a higher resolution bucket.
We are still testing out Timescale, of course. But so far, it's been holding up its end of the bargain. The fact that Timescale is "just an extension" built for Postgres also makes it a less risky choice and offers a lot of flexibility; if Timescale doesn't work out, we could still work with Postgres, and that IMHO is a very nice thing.