[roskilli]

That's interesting, I had not heard of ClickHouse as a backend for Graphite with an inverted index. Let me know if you have any links to that.

I'm assuming this is an out of process inverted index used alongside ClickHouse? Or is it more of a secondary table contained by ClickHouse which can be searched to find the metrics, then the data is looked up?

The latter scales not as well with billions of unique metrics since it's always a scan across the unique metrics stored in the time window your query searches for (since any arbitrary dimensions can be specified, all must be evaluated). This is the drawback of PromHouse which is an implementation of Prometheus remote storage on top of ClickHouse - and the major reason why PromHouse was only ever a proof of concept rather than a production offering.