OrientDB is an open source NoSQL database management system written in Java. It is the 2nd Generation Distributed Graph Database, supporting graph, document, key/value, and object models, but the relationships are managed as in graph databases with direct connections between records. OrientDB is incredibly fast: it can store 220,000 records per second on common hardware. Even for a Document based database, the relationships are managed as in Graph Databases with direct connections among records. You can traverse parts of or entire trees and graphs of records in a few milliseconds. Supports schema-less, schema-full and schema-mixed modes. Has a strong security profiling system based on user and roles and supports SQL amongst the query languages. Thanks to the SQL layer, it's straightforward to use for those skilled in the relational database world.