Pass-through datasources can be natively queried by Pyramid with direct queries. This means that the data does not need to be pre-processed or copied by Pyramid (or any other technology) before it can be queried by users.
When this option is selected, Pyramid will take the relationship definition from the database that you are connecting to; when this option is not selected, Pyramid's heuristics logic will detect the relationships.
Click here for a list of datasources that can be queried directly.
Note: MS Analysis Services (OLAP and Tabular) can be directly queried using their existing cubes and tabular models.