Most of the Postgres vs Mongo arguments I see online are based on assumptions that are either super outdated or just kind of technically wrong. The same topics keep coming up over and over on reddit, youtube, or whatever, and I wanted to write some of them down.
"PostgreSQL JSONB is basically MongoDB"
JSONB lets Postgres store documents, but it doesn't turn Postgres into a document database. Mongo's storage engine, replication, sharding, aggregation framework, indexing, update semantics, and query engine were all designed around documents from day one. JSONB is bolted onto a relational engine.
It's still really useful. But "just use JSONB" is kind of like saying "just throw a truck bed on a sedan and now it's a pickup." Like, technically there's overlap, but they're still doing different things.
"MongoDB is schemaless"
