In the past three years, the United States, the European Union, and Japan have each moved aggressively to develop their own plans for achieving exascale computing in the next decade. Such concerted planning by the traditional leaders of HPC speaks eloquently about both the substantial rewards that await the success of such efforts, and about the unprecedented technical obstacles that apparently block the path upward to get there. But while these exascale initiatives have understandably focused on the big challenges of exascale for hardware and software architecture, the relatively recent emergence of the phenomena of Big Data in a wide variety of scientific fields represents a tectonic shift that is transforming the entire research landscape on which all plans for exascale computing must play out. The NSF workshop on Big Data and Extreme-scale Computing (BDEC) is premised on the idea that we must begin to systematically map out and account for the ways in which the major issues associated with Big Data intersect with, impinge upon, and potentially change the national (and international) plans that are now being laid for achieving exascale computing.