MongoDB Associate Developer (Python)

What's on the exam

1. Domain 1: MongoDB Overview and the Document Model

   8 %

   Databases, collections and documents; BSON value types (ObjectId, Date, Decimal128, arrays, embedded documents); flexible schemas: documents of different shapes in one collection; the _id field.

   Practice domain 1 →

2. Domain 2: CRUD

   51 %

   Inserts, replacement and $set updates, upserts, updateMany, findOneAndUpdate, deletes; equality, array, comparison, $in, $elemMatch and logical queries; sort, limit, projection, cursors, counting; Atlas Search; aggregation with $match, $group, $lookup, $out.

   Practice domain 2 →

3. Domain 3: Indexes

   17 %

   Single-field, compound, multikey and unique indexes; the ESR guideline for equality, sort and range; indexes that support sorts; counting a collection's indexes; write and storage trade-offs; reading explain output (COLLSCAN versus IXSCAN, keys and documents examined).

   Practice domain 3 →

4. Domain 4: Data Modeling

   4 %

   Embedding versus referencing for one-to-one, one-to-many and many-to-many relationships; data that is accessed together is stored together; schema design patterns.

   Practice domain 4 →

5. Domain 5: Tools and Tooling

   2 %

   mongosh, MongoDB Compass, Atlas Data Explorer and the database tools (mongodump, mongorestore, mongoimport, mongoexport).

   Practice domain 5 →

6. Domain 6: Drivers

   18 %

   PyMongo: MongoClient and connection strings, reusing one client, databases and collections, inserting, finding and updating from Python, cursors, BSON types from Python (ObjectId, datetime), aggregation pipelines, error handling and transactions with sessions.

   Practice domain 6 →

Domain names and weights come from the official MDB-DEV-PY exam objectives (checked 2026-10-28). Always check it for the authoritative scope.

Includes 55 performance-style items (put in order, match, read an exhibit) — practice them with the “Order / match” filter.