Apache HBase is an open source, non-relational database that runs on top of the Hadoop Distributed File System (HDFS) and is written in Java. It is columnar and provides fault-tolerant storage and quick access to large quantities of sparse data. Sparse data means small amounts of information which are caught within a large collection of unimportant data, such as finding the 50 largest items in a group of 2 billion records. HBase features compression, in-memory operation, and Bloom filters on a per-column basis.