Big Data Benchmarking 6th International Workshop, WBDB 2015, Toronto, ON, Canada, June 16-17, 2015 and 7th International Workshop, WBDB 2015, New Delhi, India, December 14-15, 2015, Revised Selected Papers - Rabl, Tilmann; Nambiar, Raghunath; Baru, Chaitanya; Bhandarkar, Milind; Poess, Meikel; Pyne, Saumyadipta (Springer International Publishing : Imprint: Springer, 2016)