## 1.1.2 Key Features 

## High Performance 

MongoDB provides high performance data persistence. In particular, 

• Support for embedded data models reduces I/O activity on database system. 

• Indexes support faster queries and can include keys from embedded documents and arrays. 

## High Availability 

To provide high availability, MongoDB’s replication facility, called replica sets, provide: 

• automatic failover. 

• data redundancy. 

A replica set (page 559) is a group of MongoDB servers that maintain the same data set, providing redundancy and increasing data availability. 

## Automatic Scaling 

MongoDB provides horizontal scalability as part of its core functionality. 

• Automatic sharding (page 661) distributes data across a cluster of machines. 

• Replica sets can provide eventually-consistent reads for low-latency high throughput deployments. 

