Aggregation in MongoDB Compass

What is Aggregation in MongoDB?

Aggregation in MongoDB is used to process and transform multiple documents and even data across collections.

Here’s what aggregation lets you do:

• Group values to produce a single summarized output

• Run calculations (like sums, averages, counts)

• Filter, sort, and reshape data — all in one go

MongoDB uses an aggregation pipeline.

• Think of it as a conveyor belt: data flows through multiple stages.

• Each stage processes the data and passes the output to the next stage.
  
  
  

Demo Setup – Movie Ticket Booking System

For this guide, I created a simple movie ticket booking system.

We’ll focus on the users collection for our aggregation demo.

Inside every collection in Compass, there’s an Aggregation tab — this is where all the action happens.

Saving Pipelines

Once you’ve built a pipeline you like, you can save it for future use.

Saved pipelines are useful when you want to reuse complex queries.

Viewing Saved Pipelines

You can create multiple pipelines in a single collection.

To view them:

• Click the folder icon.

• You’ll see a list of saved pipelines for that collection.
  
  
  

  
  
  
  
  
  

  
  
  

  
  

Creating a Stage in the Pipeline

Each pipeline is made up of multiple stages.

• Each stage does one job (filtering, grouping, sorting, etc.).

• The output of one stage becomes the input for the next.

You can write a query for each stage, and the output appears on the right side instantly.

Adding a New Stage

Need another stage? Just click the ‘+ Add Stage’ icon.

Compass makes it easy to stack as many stages as you need.

Deleting a Stage

Any stage can be deleted by clicking the delete (trash) icon.

Turning Off a Stage

If you don’t want to delete a stage but don’t need it right now, you can toggle it off. This way, it won’t affect the pipeline, but you can turn it back on later.

Creating a View

You can create a View from your pipeline.

A View is like a “virtual collection” that stores the final output of your pipeline in read-only mode.

Viewing the View

Once you create a View, you can open it like any other collection — it shows the final, read-only output of your pipeline.

Updating a View

If you want to tweak the pipeline behind a View:

• Click Edit View — Compass takes you back to the Aggregation tab.

• Add or remove stages, then click Update View.

Conclusion

Aggregation in MongoDB Compass takes the complexity out of building queries.

With just a few clicks, you can:

• Build multi-stage pipelines

• Save and reuse them

• Create read-only Views for reporting

MongoDB Compass makes it visual, intuitive, and beginner-friendly — so you can spend less time fighting syntax and more time analyzing data.

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