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)

Sharding setup

Sharding is performed at the collection level. We can have collections that we don't want or need to shard for several reasons. We can leave these collections unsharded.

These collections will be stored in the primary shard. The primary shard is different for each database in MongoDB.

The primary shard is automatically selected by MongoDB when we create a new database in a sharded environment. MongoDB will pick the shard that has the least data stored at the moment of creation.

If we want to change the primary shard at any other point, we can issue the following command:

> db.runCommand( { movePrimary : "mongo_books", to : "UK_based" } )

We thus move the database named mongo_books to the shard named UK_based.

Choosing the shard key

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