When the data falls into a big table, HBase will store it, search it, and automatically share the table across multiple nodes so MapReduce jobs can run locally. The billions of rows of data go in, and then the local versions of the jobs can query them.
The code does not offer the full ACID guarantees of full-function databases, but it does offer a limited guarantee for some local changes. All mutations in a single row will succeed or fail together.
The system, often compared to Google's BigTable, can be found at http://hbase.apache.org. The image at left shows a screenshot from HareDB, a GUI client for working with HBase.