content_image/662498.jpg
## Data Modification 

Data modification refers to operations that create, update, or delete data. In MongoDB, these operations modify the data of a single collection . For the update and delete operations, you can specify the criteria to select the documents to update or remove. 

In the following diagram, the insert operation adds a new document to the users collection. 

<img src='content_image/662498.jpg'>

See Write Operations Overview (page 74) for more information. 

## 3.1.2 Related Features 

## Indexes 

To enhance the performance of common queries and updates, MongoDB has full support for secondary indexes. These indexes allow applications to store a view of a portion of the collection in an efficient data structure. Most indexes store an ordered representation of all values of a field or a group of fields. Indexes may also enforce uniqueness (page 504), store objects in a geospatial representation (page 494), and facilitate text search (page 500). 

