Having written a small, bespoke query engine (why? long story not for today, but mainly it was super-optimized for a very particular type of query, and very fast, with 10-50us average query times), I don't ever want to do it again except if -and only if- the performance we can wring out of it is absolutely essential and otherwise unobtainable. I'd rather use an off-the-shelf query engine any day and every day.

I would happily work on query engines, it's just I don't recommend using bespoke ones unless absolutely necessary.

I think you'll come around eventually.