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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
Pythia is another smaller option that seems to have pretty good performance. As well as FLAN. Both of those are okay for commercial use AFAIK (though double check for yourself).
NOTE:
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Hence, a higher number means a more popular project.