Peer Data Management Systems (PDMS) currently gain attention at an emerging scale in order to cope with the needs of growing organizational integration. Efficient query processing, as one of the main requirements in these systems, provides three major challenges: achieving robustness, scalability and self organization. In this paper we deal with the physical aspects of these requirements. We introduce an adaptive maintenance technique based on query feedback for keeping routing filters, used to optimize routing, up-to-date. These filters are applied in conjunction with an iterative query processing strategy and we show that this can improve robustness and scalability of query processing in distributed data management systems.