Book Image

Practical MongoDB Aggregations

By : Paul Done
Book Image

Practical MongoDB Aggregations

By: Paul Done

Overview of this book

Officially endorsed by MongoDB, Inc., Practical MongoDB Aggregations helps you unlock the full potential of the MongoDB aggregation framework, including the latest features of MongoDB 7.0. This book provides practical, easy-to-digest principles and approaches for increasing your effectiveness in developing aggregation pipelines, supported by examples for building pipelines to solve complex data manipulation and analytical tasks. This book is customized for developers, architects, data analysts, data engineers, and data scientists with some familiarity with the aggregation framework. It begins by explaining the framework's architecture and then shows you how to build pipelines optimized for productivity and scale. Given the critical role arrays play in MongoDB's document model, the book delves into best practices for optimally manipulating arrays. The latter part of the book equips you with examples to solve common data processing challenges so you can apply the lessons you've learned to practical situations. By the end of this MongoDB book, you’ll have learned how to utilize the MongoDB aggregation framework to streamline your data analysis and manipulation processes effectively.
Table of Contents (20 chapters)
2
Part 1: Guiding Tips and Principles
7
Part 2: Aggregations by Example
16
Afterword

Multi-field join and one-to-many

The previous example illustrated how to solve a one-to-one join. However, you may need to perform a one-to-many join, where a document in the first collection maps to potentially many records in the second collection. Here, you will learn how to achieve this in a pipeline.

Scenario

You want to generate a report to list all the orders made for each product in 2020. To achieve this, you need to take a shop's products collection and join each product record to all its orders stored in an orders collection. There is a one-to-many relationship between both collections, based on a match of two fields on each side. Rather than joining on a single field such as product_id (which doesn't exist in this dataset), you need to use two common fields to join (product_name and product_variation).

Note

The requirement to perform a one-to-many join does not mandate the need to join the two collections by multiple fields on each side. However, in...