Mongo has its weaknesses, yes its main strength is cited as its simplicity, or that its quick to get something out the door. I agree with your last comment. I

Mongo has its weaknesses, yes its main strength is cited as its simplicity, or that its quick to get something out the door. I agree with your last comment. I can't help but to laugh at people who think they would get away with designing a database with no schema. Schemaless for me meant that unless you enforce constraints, there won't be any. There's a reason why there are ORMs even though Mongo drivers are sufficient for most cases. 1) I've always designed my data with future changes in mind. I often spend up to an hour thinking of possibilities of data that I want to store in a collection, before writing the schema. The flexibility i have with Mongo is that if I think I need a field but am unsure of the exact data type to store, i.e. is it a string or array of strings, or array of objects with strings? In that case I just leave the field as an object and change it later. The plus being that as long as I haven't stored anything with that field, I can always change its type without a 'migration script'. I've only needed to 'migrate' by updating documents 4-5 time. When GeoJSON landed, and a few other times when I needed small changes to my data. 3) The only way I can think of enforcing constraints on < 3.2 is through indices, which is insufficient. Most ORMs do the enforcing. I've never needed to enforce them at an app level. I've used MongoDB primarily for its Geo support, and JSON enabling me to get things done quicker relative to maintaining SQL tables. I've got a small but interesting use case, public transit. https://movinggauteng.co.za https://movinggauteng.co.za and https://rwt.to https://rwt.to. When I started with the projects, PostgreSQL + PostGIS felt like a black box, and I wanted something that would give me ease and flexibility. At the time hstore was the talk of the day, but seemed to not meet my needs. It would now with JSON, but I'll stick with Mongo for now.