Book Image

Mastering MongoDB 3.x

By : Alex Giamas
Book Image

Mastering MongoDB 3.x

By: Alex Giamas

Overview of this book

MongoDB has grown to become the de facto NoSQL database with millions of users—from small startups to Fortune 500 companies. Addressing the limitations of SQL schema-based databases, MongoDB pioneered a shift of focus for DevOps and offered sharding and replication maintainable by DevOps teams. The book is based on MongoDB 3.x and covers topics ranging from database querying using the shell, built in drivers, and popular ODM mappers to more advanced topics such as sharding, high availability, and integration with big data sources. You will get an overview of MongoDB and how to play to its strengths, with relevant use cases. After that, you will learn how to query MongoDB effectively and make use of indexes as much as possible. The next part deals with the administration of MongoDB installations on-premise or in the cloud. We deal with database internals in the next section, explaining storage systems and how they can affect performance. The last section of this book deals with replication and MongoDB scaling, along with integration with heterogeneous data sources. By the end this book, you will be equipped with all the required industry skills and knowledge to become a certified MongoDB developer and administrator.
Table of Contents (13 chapters)

Architectural overview

MongoDB's replication can be seen in the following diagram:

The primary server is the only one that can take writes at any time. The secondary servers are in a hot standby state, ready to take over if the primary server fails. Once the primary server fails, an election takes place regarding which secondary server will become primary.

We can also have arbiter nodes. Arbiter nodes do not hold any data and their sole purpose is only to participate in the election process.

We must always have an odd number of nodes (including arbiters). Three, five, and seven are all fine so that in the event of the primary (or more servers) failing we have a majority of votes in the election process.

When other members of a replica set don't hear from the primary for more than 10 seconds (configurable), an eligible secondary...