Data source privacy settings

• Just as relational databases such as SQL Server consider many potential query plans, the M engine also searches for the most efficient methods of executing queries given the data sources and query logic defined.
• In the absence of data source privacy settings, the M engine is allowed to consider plans that merge disparate data sources. For example, a local text file of customer names can be merged with an external or third-party server given the better performance of the server.
• Defining privacy settings isolates data sources from these operations. Given the increased likelihood of local resource usage, query performance may be reduced.