Inverted Index Support for Numeric Search

Abstract

Today's search engines are increasingly required to broaden their capabilities beyond free-text search. More complex features, such as supporting range constraints over numeric data, are becoming common; structured search over XML data will soon follow. This is particularly true in the enterprise search domain, where engines attempt to integrate data from the web and corporate knowledge portals with data residing in proprietary databases. In this paper we extend previous schemes by which an inverted-index-based search engine can efficiently support queries that contain numeric restrictions in addition to standard, free-text portions. Furthermore, we analyze both the known schemes and our extensions in terms of index-build time, index space, and query processing time. We show how to maximize query processing performance while respecting limits on index size and build time, or conversely, how to minimize index space and build time while maintaining guarantees on runtime performance. Thus, we concisely analyze the trade-off between index size and build time, and runtime performance. Finally, we present experimental results that demonstrate significant performance benefits attained by our method, as compared to alternative approaches.