Melissa Coates has a nice choose-your-own-adventure story around Azure SQL Data Warehouse:
Q4: How large is your database?
It is difficult to pinpoint an exact number for the absolute minimum size recommended for Azure SQL DW. Many data professionals in the industry see the minimum “practical” data size for Azure SQL DW in the 1-4TB range. Microsoft documentation has recently stated as low as 250GB for a minimum size. Since Azure SQL DW is an MPP (massively parallel processing) system, you experience a significant performance penalty with small data sizes because of the overhead incurred to distribute and consolidate across the nodes (which are distributions in a “shared-nothing” architecture). We recommend Azure SQL DW for a data warehouse which is starting to approach 1TB and expected to continue growing.
Great advice here. I’ve heard too often of people looking at the name “Azure SQL Data Warehouse” and figuring that because they have data warehouses on-prem, this is the appropriate analog. Azure SQL DW is not a typical data warehousing environment; it’s more of a specialized tool than that, so click through to see if it fits your needs.