MongoDB is a high-performance, open source, schema-free document-oriented data store that's easy to deploy, manage and use. It's network accessible, written in C++ and offers the following features :

• Full index support, including on inner objects
• Query profiling
• Replication and fail-over support
• Efficient storage of binary data including large objects (e.g. videos)
• Auto-sharding for cloud-level scalability (Q209)

High performance, scalability, and reasonable depth of functionality are the goals for the project. Deep transaction support is not a goal of the system.