Minimal probing: supporting expensive predicates for top-k queries

This paper addresses the problem of evaluating ranked top-? queries with expensive predicates. As major DBMSs now all support expensive user-defined predicates for Boolean queries, we believe such support for ranked queries will be even more important: First, ranked queries often need to model user-specific concepts of preference, relevance, or similarity, which call for dynamic user-defined functions. Second, middleware systems must incorporate external predicates for integrating autonomous sources typically accessible only by per-object queries. Third, fuzzy joins are inherently expensive, as they are essentially user-defined operations that dynamically associate multiple relations. These predicates, being dynamically defined or externally accessed, cannot rely on index mechanisms to provide zero-time sorted output, and must instead require per-object probe to evaluate. The current standard sort-merge framework for ranked queries cannot efficiently handle such predicates because it ...

• Type: Conference
• Year: 2002
• Where: SIGMOD
• Authors: Kevin Chen-Chuan Chang, Seung-won Hwang
• Keywords: Database, Expensive Predicates, Expensive User-defined Predicates, Ranked Queries, SIGMOD 2002