HBase Goes Realtime
HBase release their new version, in which largely rewrites its previous versions, and enhances its performance in order of magnitude . HBase is the Hadoop database. Its an open-source, distributed, column-oriented store modeled after the Google paper, Bigtable: A Distributed Storage System for Structured Data by Chang et al. Just as Bigtable leverages the distributed data storage provided by the Google File System, HBase provides Bigtable-like capabilities on top of Hadoop.
HBase's goal is the hosting of very large tables -- billions of rows X millions of columns -- atop clusters of commodity hardware. Try it if your plans for a data store run to big.
Here is a presentation that summarizes the new version : http://wiki.apache.org/hadoop-data/attachments/HBase(2f)HBasePresentations/attachments/HBase_Goes_Realtime.pdf