On the translation of relational queries into iterative programs

This paper investigates the problem of translating set-oriented query specifications into iterative programs. The translation uses techniques of functional programming and program transformation. We present two algorithms that generate iterative programs from algebra-based query specifications. The first algorithm translates query specifications into recursive programs. Those are simplified by sets of transformation rules before the algorithm generates the final iterative form. The second algorithm uses a two-level translation that generates iterative programs faster than the first algorithm. On the first level a small set of transformation rules performs structural simplification before the functional combination on the second level yields the final iterative form.