MongoDB Cookbook - Second Edition

Creating and understanding sparse indexes

Schemaless design is one of the fundamental features of Mongo. This allows documents in a collection to have disparate fields, with some fields present in some documents and absent in others. In other words, these fields might be sparse, which might have already given you a clue on what sparse indexes are. In this recipe, we will create some random test data and see how sparse indexes behave against a normal index. We shall see the advantages and one major pitfall of using a sparse index.

Getting ready

For this recipe, we need to create a collection called sparseTest. We will require a server to be up and running. Refer to the Installing single node MongoDB recipe from Chapter 1, Installing and Starting ...