Discussion on HackerNews and Lobsters. MongoDB has recently released a new query engine coming in version 7.0. I was one of the people working on this engine during my 2 years in MongoDB and I would like to share some technical details about it. Disclaimer: Prior to writing this article, I have contacted my ex-colleagues at MongoDB to ensure that it does not conflict with their plans. They gave me the green light, provided I send them the draft before publishing, which I did.