Learning MongoDB Aggregations in 10 Minutes

In this presentation I a attempt to cover the essence of MongoDB Aggregations In 10 minutes, Aggregations enable you to write complex queries in when working with MongoDB. You can perform ETL fairly quickly, but you must ensure that you adhere to best practices. Specifically review the order of your pipeline stages, indexing strategy and the type of stages(blocking or non-blocking). You can use the MongoDB Aggregation framework from your application(Java, NodeJS, Python etc).

1. MongoDB Aggregations in 10 Minutes A Quick Guide to Mastering MongoDB’s Aggregation Framework

2. Agenda Introduction to Aggregations Aggregation Pipeline Common Stages in Aggregation Example Queries Use Cases for Aggregations Conclusion

3. Introduction to MongoDB Aggregations

4. Aggregation Pipeline Overview

5. Discrete Processing Stages Stages can be streaming or blocking; favour the usage of streaming stages The order of stages matters, apply best practices Stages are easier to debug and maintain

6. Common Aggregation Stages

7. Stage Example 1: $match and $group $match and $group Example: db.sales.aggregate ([ { $match: { status: 'completed' } }, { $group: { _id: '$product', total: { $sum: '$amount' } } } ]) Explanation: Filters documents where status is 'completed'. Groups by product and sums up the amount.

8. Stage Example 2: $project and $sort $project and $sort Example: db.sales.aggregate ([ { $project: { product: 1, amount: 1, profit: { $subtract: ['$revenue', '$cost'] } } }, { $sort: { profit: -1 } } ]) Explanation: Projects product, amount, and calculates profit. Sorts documents by profit in descending order.

9. Real-World Use Case: Monthly Sales Report Problem: Generate a monthly sales report showing total sales and average sale amount for each category. Solution: db.sales.aggregate ([ { $match: { date: { $ gte : new ISODate ('2023-01-01'), $ lt : new ISODate ('2023-02-01') } } }, { $group: { _id: '$category', totalSales : { $sum: '$amount' }, avgSale : { $ avg : '$amount' } } } ]) Explanation: Filters sales for January 2023. Groups by category and calculates total and average sales.

10. Aggregation Performance Tips

11. Conclusion and Further Learning Conclusion Aggregations in MongoDB provide powerful data transformation tools. Pipelines combine multiple stages for complex queries. Practice with real datasets to master these concepts. Further Reading: MongoDB Documentation on Aggregations MongoDB University Courses