The 10 Skills I Was Missing as a MongoDB User

When I first started using MongoDB, I didn’t have a plan beyond “install it and hope for the best.” I had read about how flexible it was, and it felt like all the developers swore by it, so I figured I’d give it a shot. I spun it up, built my first application, and got a feature working.

But I felt like something was missing.

It felt clunky. My queries were longer than I expected, and performance wasn’t great; I had the sense that I was fighting with the database instead of working with it. After a few projects like that, I began to wonder if maybe MongoDB wasn’t for me.

Looking back now, I can say the problem wasn’t MongoDB, but was somewhere between the keyboard and the chair. It was me. I was carrying over habits from years of working with relational databases, expecting the same rules to apply.

If MongoDB’s Skill Badges had existed when I started, I think my learning curve would have been a lot shorter. I had to learn many lessons the hard way, but these new badges cover the skills I had to piece together slowly. Instead of pretending I nailed it from day one, here’s the honest version of how I learned MongoDB, what tripped me up along the way, and how these Skill Badges would have helped.

Learning to model the MongoDB way

The first thing I got wrong was data modeling. I built my schema like I was still working in SQL– every entity in its own collection, always referencing instead of embedding, and absolutely no data duplication. It felt safe because it was familiar.

Then I hit my first complex query. It required data from various collections, and suddenly, I found myself writing a series of queries and stitching them together in my code. It worked, but it was a messy process.

When I discovered embedding, it felt like I had found a cheat code. I could put related data together in one single document, query it in one shot, and get better performance.

That’s when I made my second mistake. I started embedding everything.

At first, it seemed fine. However, my documents grew huge, updates became slower, and I was duplicating data in ways that created consistency issues. That’s when I learned about patterns like Extended References, and more generally, how to choose between embedding and referencing based on access patterns and update frequency.

Later, I ran into more specialized needs, such as pre-computing data, embedding a subset of a large dataset into a parent, and tackling schema versioning. Back then, I learned those patterns by trial and error. Now, they’re covered in badges like Relational to Document Model, Schema Design Patterns, and Advanced Schema Patterns.

Fixing what I thought was “just a slow query”

Even after I got better at modeling, performance issues kept popping up. One collection in particular started slowing down as it grew, and I thought, “I know what to do! I’ll just add some indexes.”

I added them everywhere I thought they might help. Nothing improved.

It turns out indexes only help if they match your query patterns. The order of fields matters, and whether you cover your query shapes will affect performance. Most importantly, just because you can add an index doesn’t mean that you should be adding it in the first place.

The big shift for me was learning to read an explain() plan and see how MongoDB was actually executing my queries. Once I started matching my indexes to my queries, performance went from “ok” to “blazing fast.”

Around the same time, I stopped doing all my data transformation in application code. Before, I’d pull in raw data and loop through it to filter, group, and calculate. It was slow, verbose, and easy to break. Learning the aggregation framework completely changed that. I could handle the filtering and grouping right in the database, which made my code cleaner and the queries faster.

There was a lot of guesswork in how I created my indexes, but the new Indexing Design Fundamentals covers that now. And when it comes to querying and analyzing data, Fundamentals of Data Transformation is there to help you. Had I had those two skills when I first started, I would’ve saved a lot of time wasted on trial and error.

Moving from “it works” to “it works reliably”

Early on, my approach to monitoring was simple: wait for something to break, then figure out why. If a performance went down, I’d poke around in logs. If a server stopped responding, I’d turn it off and on again, and hope for the best.

It was stressful, and it meant I was always reacting instead of preventing problems.

When I learned to use MongoDB’s monitoring tools properly, that changed. I could track latency, replication lag, and memory usage. I set alerts for unusual query patterns. I started seeing small problems before they turned into outages.

Performance troubleshooting became more methodical as well. Instead of guessing, I measured. Breaking down queries, checking index use, and looking at server metrics side by side. The fixes were faster and more precise.

Reliability was the last piece I got serious about. I used to think a working cluster was a reliable cluster. But reliability also means knowing what happens if a node fails, how quickly failover kicks in, and whether your recovery plan actually works in practice.

Those things you can now learn in the Monitoring Tooling, Performance Tools and Techniques, and Cluster Reliability skill badges. If you are looking at deploying and maintaining MongoDB clusters, these skills will teach you what you need to know to make your deployment more resilient.

Getting curious about what’s next

Once my clusters were stable, I stopped firefighting, and my mindset changed. When you trust your data model, your indexes, your aggregations, and your operations, you get to relax. You can then spend that time on what’s coming next instead of fixing what’s already in production.

For me, that means exploring features I wouldn’t have touched earlier, like Atlas Search, gen AI, and Vector Search. Now that the fundamentals are solid, I can experiment without risking stability and bring in new capabilities when a project actually calls for them.

What I’d tell my past self

If I could go back to when I first installed MongoDB, I’d keep it simple:

• Focus on data modeling first. A good foundation will save you from most of the problems I ran into.

• Once you have that, learn indexing and aggregation pipelines. They will make your life much easier when querying.

• Start monitoring from day one. It will save you a lot of trouble in the long run.

• Take a moment to educate yourself. You can only learn so much from trial and error. MongoDB offers a myriad of resources and ways to upskill yourself.

Once you have established that base, you can explore more advanced topics and uncover the full potential of MongoDB. Features like Vector Search, full-text search with Atlas Search, or advanced schema design patterns are much easier to adopt when you trust your data model and have confidence in your operational setup.