Another way to implement complex computations: functional-style SQL UDF

Whenever data-intensive computation gets so complex that it requires the use of iteration or recursion, SQL developers turn towards recursive common table expressions (CTEs). We present the results of a user study that shows how developers struggle with the unusual fixpoint semantics and awkward monolithic syntactic structure of CTEs. The study suggests that recursive user-defined functions (UDFs)---written in a style much like regular functional programs---are less prone to errors, significantly more readable, and can be authored more quickly. Since such recursive UDFs can be automatically compiled into efficiently executable CTEs, we put functional-style UDFs forward as another promising pillar to express complex computation close to the data.