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

One-to-one join

Sometimes, you need to join data between two collections, where one document in the first collection maps to one, and only one, document in the second collection. This section provides an example of performing this one-to-one join using the $lookup aggregation stage in MongoDB.

Note

For this example, you require MongoDB version 4.4 or above. This is because you will use the $first array operator introduced in version 4.4.

Scenario

You want to generate a report to list all shop purchases for 2020, showing the product's name and category for each order, rather than the product's ID. To achieve this, you need to take the customer orders collection and join each order record to the corresponding product record in the products collection. There is a many-to-one relationship between both collections, resulting in a one-to-one join when matching an order to a product. The join will use a single field comparison between both sides, based on the product...