Apparatus, systems, and methods may operate to receive an original query plan, to transform the original query plan into an equivalent executable compact query plan, and to store the compact query plan on a machine readable device. Further activities may include computing maximal source sub-queries associated with the compact query plan, and computing semi-join reductions of the maximal source sub-queries to provide an executable derivative query plan, which may also be stored on a machine readable device. Additional apparatus, systems, and methods are described.