Whether it is data warehouses or marts, data lakes, or reservoirs, the IT industry has a penchant for metaphor. The subliminal images conjured in the human mind by the above terms are, in my opinion, of critical importance in guiding thinking about the fundamental meanings and architectures of these constructs. Thus, a data warehouse is a large, cavernous, but well-organized location for gathering and storing data prior to its final use and a place where consumers are less than welcome for fear of being knocked down by a forklift truck. A data mart, on the other hand, creates an image of something between your friendly corner store and Walmart.