I disagree with the last statement: "While there is room for apple-oranges none of these seem to be successful so far. It seems to be common sense that SQL-on-Hadoop just like an apple-on-orange is not a great idea in terms of performance. Limited success in attempts such as Hive on Hadoop seem to prove this so far. Using low-level programming languages such as C++ with RDBMSs is also possible (see e.g. SQLAPI). However, described above advantages of RDBMSs most likely vanish if you do so."

Actian Vortex has shown that you can have a fully ACID compliant database running on top of Hadoop all while providing exceptional performance. http://wwwcdn.actian.com/wp-content/uploads/2014/06/AAP-Hado...