Book Image

Learn MongoDB 4.x

By : Doug Bierer
Book Image

Learn MongoDB 4.x

By: Doug Bierer

Overview of this book

When it comes to managing a high volume of unstructured and non-relational datasets, MongoDB is the defacto database management system (DBMS) for DBAs and data architects. This updated book includes the latest release and covers every feature in MongoDB 4.x, while helping you get hands-on with building a MongoDB database app. You’ll get to grips with MongoDB 4.x concepts such as indexes, database design, data modeling, authentication, and aggregation. As you progress, you’ll cover tasks such as performing routine operations when developing a dynamic database-driven website. Using examples, you’ll learn how to work with queries and regular database operations. The book will not only guide you through design and implementation, but also help you monitor operations to achieve optimal performance and secure your MongoDB database systems. You’ll also be introduced to advanced techniques such as aggregation, map-reduce, complex queries, and generating ad hoc financial reports on the fly. Later, the book shows you how to work with multiple collections as well as embedded arrays and documents, before finally exploring key topics such as replication, sharding, and security using practical examples. By the end of this book, you’ll be well-versed with MongoDB 4.x and be able to perform development and administrative tasks associated with this NoSQL database.
Table of Contents (22 chapters)
Section 1: Essentials
Section 2: Building a Database-Driven Web Application
Section 3: Digging Deeper
Section 4: Replication, Sharding, and Security in a Financial Environment
Working with Complex Documents Across Collections

Document references

The third approach, most commonly used by MongoDB developers, is to use document references. In this approach, instead of storing a partial document (that is, a building block), or instead of storing an entire document (embedded document), you only store the equivalent of a foreign key, which then allows you to perform a secondary lookup to retrieve the needed information.

Although you could conceivably store the _id (ObjectID instance) field as the reference, it is considered a best practice in the MongoDB world to have a developer-generated unique key of some sort, which can be used to perform the lookup.

As an example, when storing loan information, instead of storing partial or complete borrower and lender information, just store the userKey fields. This can then be used in conjunction with find() to retrieve lender or borrower information. You will note that this is the approach taken with BigLittle Micro Finance Ltd. When creating a loan document, the userKey...