InfluxDB query addon proposal

I would agree

But we can already do that within rules.

A better use case for a kind of “general query”? (I’m imagining the mechanism here would be a command/argument string where we could set a database specific query e.g. SQL)

A metering or monitoring application, where we want to get the data for some past calendar month. Not possible in current persistence, where you can get only from past point X to now.