GraphLab distributed graph database

GraphLab is a graph-based, high performance, distributed computation framework written in C++.  While GraphLab was originally developed for Machine Learning tasks, it has found great success at a broad range of other data-mining tasks; out-performing other abstractions by orders of magnitude.
GraphLab Features:

• A unified multicore and distributed API: write once run efficiently in both shared and distributed memory systems
• Tuned for performance: optimized C++ execution engine leverages extensive multi-threading and asynchronous IO
• Scalable: GraphLab intelligently places data and computation using sophisticated new algorithms
• HDFS Integration: Access your data directly from HDFS
• Powerful Machine Learning Toolkits: Turn BigData into actionable knowledge with ease