Two years ago, I published this post detailing how I had refactored the Query of Query support in Lucee to be much better and also much faster:
I removed the single-threaded HSQLDB callback for grouped/aggregate and distinct selects and tuned the performance. QoQ's are a bit of a polarizing feature in CFML. They've suffered in the past from poor support and poor performance which has caused a lot of people to avoid them. There are certainly places where queryMap(), queryFilter(), and queryReduce() are the best approach, but there are also times where you simply can't beat the readability and conciseness of an ordered, aggregated select. I know developers who tell me they never use "reduce" higher order functions because they are too confusing, but I've never met a developer who didn't understand "GROUP BY department"!
I've got several other ideas to increase the feature set of QoQ in CFML including native support for INNER and OUTER joins as well as this idea of exposing CFML string, number, and date functions directly in QoQ. I've also put in a handful of tickets for Adobe ColdFusion to invite them to follow in the improvements I've added to Lucee. I'd send them pulls, if I could : (