M3QL still is the primary query language internally, however the query service is still being rebuilt in open source M3 - so it’s not available just yet.

As to why we’ve kept it, there’s been such a large amount of functions we’ve added over time that don’t really have an alternative in say PromQL, etc - so we aim to offer both PromQL and M3QL in open source land and letting end users use either one. I don’t think either are better than the other one, they’re just different flavors - function expansion vs pipe based, etc.

Here’s the list of functions, you can kind of get a sense of what I’m talking about just by looking at the list: http://m3db.github.io/m3/query_engine/architecture/functions...

We are working on making WarpScript (http://www.warp10.io) able to fetch data from M3, so you can benefit from 850+ functions for analyzing your time series data.