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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.
If you mean strictly without FFI, then probably Shinmera's recommendation. If you mean portable, then osicat is worth looking at. Sadly, it's unmaintained now, but may work, and could use a maintainer.
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