Just to tail on the “Postgres is a better document DB than Mongo” theme, there’s now a QuickJS procedural extension for postgres (in addition to the earlier but clunkier plv8):

https://github.com/plv8/pljs https://bellard.org/quickjs/quickjs.html

The rub is that you can yeet any document data you like into JSONB columns, and mung them efficiently and freely with JS — taking all the upsides of Mongo, yet letting you merge them seamlessly with the full capabilities of PG’s relational model.