Book Image

Mastering MongoDB 4.x - Second Edition

By : Alex Giamas
Book Image

Mastering MongoDB 4.x - Second Edition

By: Alex Giamas

Overview of this book

MongoDB is the best platform for working with non-relational data and is considered to be the smartest tool for organizing data in line with business needs. The recently released MongoDB 4.x supports ACID transactions and makes the technology an asset for enterprises across the IT and fintech sectors. This book provides expertise in advanced and niche areas of managing databases (such as modeling and querying databases) along with various administration techniques in MongoDB, thereby helping you become a successful MongoDB expert. The book helps you understand how the newly added capabilities function with the help of some interesting examples and large datasets. You will dive deeper into niche areas such as high-performance configurations, optimizing SQL statements, configuring large-scale sharded clusters, and many more. You will also master best practices in overcoming database failover, and master recovery and backup procedures for database security. By the end of the book, you will have gained a practical understanding of administering database applications both on premises and on the cloud; you will also be able to scale database applications across all servers.
Table of Contents (20 chapters)
Free Chapter
1
Section 1: Basic MongoDB – Design Goals and Architecture
4
Section 2: Querying Effectively
10
Section 3: Administration and Data Management
15
Section 4: Scaling and High Availability

Aggregation operators

In this section, we will learn how to use aggregation operators. Aggregation operators are divided into two categories. Within each stage, we use expression operators to compare and process values. Between different stages, we use aggregation stage operators to define the data that will get passed on from one stage to the next, as it is considered to be in the same format.

Aggregation stage operators

An aggregation pipeline is composed of different stages. These stages are declared in an array and executed sequentially, with the output of every stage being the input of the next one.

The $out stage has to be the final stage in an aggregation pipeline, outputting data to an output collection by replacing...