Mongodb now supports effectivly "Joins" in its aggregation framework, so it can do some relational style data representation. The latest versions also support transactions.
Yeah but they do not recommend using that. I think the one nosql afficianado in my team spoke with mongo support and they recommended reassessing our document structure for it. (So a migration after all... )
Also in their blogpost [1], about $lookup they say:
We’re still concerned that $lookup can be misused to treat MongoDB like a relational database. But instead of limiting its availability, we’re going to help developers know when its use is appropriate, and when it’s an anti-pattern. In the coming months, we will go beyond the existing documentation to provide clear, strong guidance in this area.
Also in their blogpost [1], about $lookup they say:
We’re still concerned that $lookup can be misused to treat MongoDB like a relational database. But instead of limiting its availability, we’re going to help developers know when its use is appropriate, and when it’s an anti-pattern. In the coming months, we will go beyond the existing documentation to provide clear, strong guidance in this area.
[1] https://www.mongodb.com/blog/post/revisiting-usdlookup