DependentJoin joins an input relation with the product of a dependent execution unit. The dependent execution unit can be parameterized with data from the input relation or from the calling execution unit. The join itself is unconditional. Because the dependent execution unit is parameterized, however, the contents of the dependent relation can be different for every input row. The join is either nesting or flat:
Each input row is augmented by a single iterator column that contains the dependent execution unit’s output rows.
Each input row is augmented by all the columns of the dependent execution unit’s output rows.
