MongoDB vs PostgreSQL — MongoDB Technical Interview Questions & Answers

Side-by-side comparison table.

MongoDB vs PostgreSQL

  • Simple meaning: PostgreSQL is a strong relational DB (and can store JSONB). MongoDB is document-first.
  • If you need SQL, views, heavy joins, Postgres shines. If the document is the record, Mongo is natural.
  • Postgres JSONB vs Mongo documents: both store JSON-like data; query style and ops differ.
  • Interview tip: Don’t say Postgres cannot store JSON. Say document-first vs relational-first.

Technical Interview Tip: Relational-first vs document-first.

Code Examples for MongoDB vs PostgreSQL

MongoDB vs PostgreSQL — working example

// Collection "users" holds BSON documents (JSON-like):
db.users.insertOne({
  name: "Ada",
  email: "ada@example.com",
  age: 36,
  skills: ["Java", "MongoDB"],
  address: { city: "Pune", pin: "411001" }
})
db.users.find({ "address.city": "Pune" })

MongoDB vs PostgreSQL — mongoDB stores BSON documents in collections — flexible schema, nested fields, rich queries.

How to Explain MongoDB vs PostgreSQL to an Interviewer

Postgres vs Mongo?

SQL/joins vs documents/embed Postgres also has JSONB