Dynamic query interfaces (DQIs) are a recently developed database access mechanism that provides continuous real-time feedback to the user during query formulation. Previous work shows that DQIs are an elegant and powerful interface to small databases. Unfortunately, when applied to large databases, previous DQI algorithms slow to a crawl. We present a new incremental approach to DQI algorithms and display updates that works well with large databases, both in theory and in practice. (Also cross-referenced as UMIACS-TR-97-46