mongoDB

mongoDB is very hot now.

MongoDB (from "humongous") is an open source document database, and the leading NoSQL database. Written in C++, MongoDB features:

• Document-Oriented Storage »

  JSON-style documents with dynamic schemas offer simplicity and power.

• Full Index Support »

  Index on any attribute, just like you're used to.

• Replication & High Availability »

  Mirror across LANs and WANs for scale and peace of mind.

• Auto-Sharding »

  Scale horizontally without compromising functionality.

• Querying »

  Rich, document-based queries.

• Fast In-Place Updates »

  Atomic modifiers for contention-free performance.

• Map/Reduce »

  Flexible aggregation and data processing.

• GridFS »

  Store files of any size without complicating your stack.

• Commercial Support »

  Enterprise class support, training, and consulting available.

http://api.mongodb.org/cplusplus/2.3.1/annotated.html