Policy-Constrained Query Placement at the Edge: A Catalog Architecture, Complexity Analysis, and Latency Trade-Offs

Edge databases must coordinate replica freshness, consistency requirements, and governance restrictions despite intermittent connectivity. This study specifies an Edge-Aware Database Management System (EA-DBMS) architecture centered on the Policy-Aware Distributed Edge Catalog (PADEC). Its architectural novelty within the reviewed literature is a shared metadata interface connecting these constraints to operator placement, local transaction admission, and reintegration. This design provides a basis for keeping permitted operations local during outages and combining authorized results across sites under explicit contracts. A worked example demonstrates how joint filtering rejects prohibited and stale candidates. The analysis formalizes policy-constrained operator placement and distinguishes NP-hard general cases from three subclasses admitting polynomial-time exact solutions. A reproducible analytical evaluation derives conditional latency trade-offs from published measurements, documented proxies, and explicit assumptions. At a 10 ms proxy catalog cost, local reads benefit in one of four paired network scenarios at the low end of the published execution-time range. Under baseline assumptions, reductive aggregation becomes beneficial above approximately 401 kB per window at a reduction factor of 0.189. In the modeled mixture, global coordination reduces the mean-latency advantage. The design targets industrial telemetry, disconnected local processing, and data-residency-constrained analytics, with catalog lookup cost and matched edge–cloud execution times as priorities for empirical evaluation.