In case we have multiple Fact tables, then it is a best practice to set an Implicit Fact Column. The goal of this is to guide the BI Server to make the best choice between two possible query paths.You need to select a fact attribute (measure) as an implicit fact column.
A User may request a report where it may have only Dimensions and no Fact columns. When these are requested,the server may sometimes get confused as from which fact table should it join to fetch the data. So it joins to the nearest fact table and pulls the data through it. So the report output obtained may be different from what the user is expecting.
So, in order to avoid this kind of error, we can create a dummy fact column called Implicit Fact Column in physical layer.You can find this functionality in the general property of a subject area in the repository. Join all dimensions to this fact column in BMM Layer.In presentation layer, double click the presentation catalog or go to properties of presentation catalog.In the general tab, find the Implicit Fact Column section. So, whenever a report on Dimensions is requested it joins through dummy fact table and fetches data.