My Journey to MongoDB: C100DEV Certification

Recently (Mar 2021), I appeared for MongoDB certification and cleared the exam in the first attempt.Over the past 18 months, I have been involved in a project where i was responsible for migrating the data from Relational database to MongoDB for flexible document data model and scaling the application. As a part of project, i was involved in evaluating whether MongoDB was a right fit, and once the MongoDB was determined as a right fit, i took the responsibility of sizing ( working set and indexes) the database, schema design and MQL development, plus GraphQL API integration support via Graphene. While i was working in this, i decided to challenge my knowledge in mongodb by writing C100 DEV( MongoDB Developer certification). Since, i don’t find much blogs or posts pertaining to MongoDB Developer certification, I have decided to share my experiences about my certification Journey.

  1. Learning Materials:

MongoDB has pretty good learning portal, and all you need is get yourself enrolled in MongoDB University courses based on certification track and try to finish the every modules, quizzes and exams. Trust me, these covers vast amount of topics.

Courses required for Developer path and under each courses, i am posting which topic you should focus only based on my experience:

a. M001 — Basics of MongoDB

CRUD operations : Know about various MongoDB commands related to CRUD ( insert, delete, update- upsert), Operators ( comparison, logical, array).

b. M121 — Aggregation Framework

Please have a extensive look at various MongoDB aggregation operators and its uses such as ($project vs $addFields, $lookup, $graphlookup, $replaceroot, $group, $sample, $push, $pull, $unwind, $facet etc), Aggregation optimizations

c. M201 — Indexes and performances

Covered queries, In-memory sorting conditions, compound key indexes, sort prefix conditions, WiredTiger cache, unique and hash index, optimizations, hints, working set and sizing indexes

d. M103 — Replication and Sharding

Oplogs, Hidden and delayed nodes, replication and sharding features in 4.4 or latest release, shard keys, zone shard, mongs and config servers

e. M320 — Data modelling

One to many, one to one, many to many scenarios.

f. In addition to this, you need to know about latest release features under each mentioned topic( in my case mongoDB 4.4). Refer MongoDB documentation or study guide to know about this

You need to have solid understanding about the topics covered in every course, so please finish every quizzes, labs and exams and revise again on the topics which you are not comfortable. Though MongoDB website, M320 is optional, i would highly recommend you to finish that too as you will see a few questions in exam as well. You do not need any other materials other than this to pass this certification. MongoDB has a very good documentation

2. About the Exam:

The exam itself has 60 questions, and you have 90 minutes to complete the exam. All questions are either multiple or multi-choice questions which will test you on the topic (a–f) which i mentioned above. I think a,b and c cover 60% of questions. All questions have equal weightage, and you will not be penalized for incorrect answers, so please attempt every questions. MongoDB provides practise exams, I kind of feel it is slightly outdated w.r.t 4.4 , but it is still a good start for you. you cannot pass the exam only if u finish a-e ( see above), you need to know about the features in latest release (e.g., sharding , replication ,wiredTiger cache) and its use cases. I would say just a high level read on documentation and note taking would help. You do not need to learn in depth about each sections. Exam questions will be slightly tricky — some questions are very easy, some are medium and a few are hard. Moreover, pass mark is 490, and i don’t have any idea about of maximum mark( i believe it is 600 — but please don’t quote me on this).

3. Conclusion

I hope this post would help the people who wanted to take the developer certification in MongoDB. Also, i would like to thank for his blog post on MongoDB DBA certification. It was very useful and an extensive blog, and i would like to thank him for the wonderful post which will help candidates like me and whoever wanted to take certification.




Data Scientist - Data Engineer - Database

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Karthikeyan Chandrasekaran

Karthikeyan Chandrasekaran

Data Scientist - Data Engineer - Database

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