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)

Connecting to a replica set

Connecting to a replica set is not fundamentally different to connecting to a single server. In this section, we will show some examples using the official mongo-ruby-driver.

First we need to set our host and options objects:

client_host = ['hostname:port']
client_options = {
database: 'signals',
replica_set: 'xmr_btc'

In the preceding example, we are getting ready to connect to host:port hostname, in database signals in the replica_set xmr_btc.

Calling the initializer on Mongo::Client will now return a client object that contains a connection to our replica set and database:

client =, client_options)

The client object then has the same options as it has when connecting to a single server.

MongoDB uses auto-discovery after connecting to our client_host to identify the other members of our replica...