There is much more to MongoDB than can be fully covered in this book. This chapter covers some additional fundamentals beyond the normal database create, access, and delete operations. Designing and implementing indexes allows you to improve database performance. Also, implementing replica sets and sharding provide additional performance improvements and high availability.
MongoDB allows you to index fields in your collections that make it faster to find documents. When an index is added in MongoDB, a special data structure is created in the background that stores a small portion of a collection’s data and then optimizes the structure of that data to make it faster to find specific documents.