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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.
Yomu sounds like what you're looking for. However, it depends on Apache Tika. It's more or less a wrapper. This is a big lift though, so I don't think you'll find a native Ruby library for something like this.
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