HadoopDB : Hadoop + RDBMS

HadoopDB 是耶鲁大学的一些研究人员在进行的一个Opensource项目，类似GreenPlum,Aster Data，描述如下：

1. A hybrid of DBMS and MapReduce technologies that targets analytical workloads
2. Designed to run on a shared-nothing cluster of commodity machines, or in the cloud
3. An attempt to fill the gap in the market for a free and open source parallel DBMS
4. Much more scalable than currently available parallel database systems and DBMS/MapReduce hybrid systems.
5. As scalable as Hadoop, while achieving superior performance on structured data analysis workloads

还有一张paper ，可以看看。