On a project recently, there arose an issue where logical columns that were not explicitly added to a hierarchy where suddenly drillable! What would cause that? Did someone change a property? After careful analysis, I found out that there are 2 things that will make logical columns (not explicitly set in a hierarchy level) become drillable. But please remember and note that logical column(s) from a Logical Dimension Table source not explicitly assigned to a hierarchy level will by default be set and applied to the lowest(detail) level. This is what makes them not drillable by default. These two things are:
1. If the lowest level key that is set to “use for drilldown” is a logical column that is defined as a formula expression (such as concats of two other logical columns).
2. If the lowest level is really not the lowest level due to setting preferred drill down to another level in another dimension.
2. If the lowest level is really not the lowest level due to setting preferred drill down to another level in another dimension.
These two above will result in all the logical columns not set in the hierarchy to now be drillable.
The work around for this is to set those columns defaults to be not drillable. In order to set this, you have to go into Answers and set the system-wide defaults to “column heading interaction” and “value interaction” to “No Interaction. This is done within the column properties via the “column format” tab.