How to ConQueR why-not questions

One useful feature that is missing from today’s database systems is an explain capability that enables users to seek clarifications on unexpected query results. There are two types of unexpected query results that are of interest: the presence of unexpected tuples, and the absence of expected tuples (i.e., missing tuples). Clearly, it would be very helpful to users if they could pose follow-up why and why-not questions to seek clarifications on, respectively, unexpected and expected (but missing) tuples in query results. While the why questions can be addressed by applying established data provenance techniques, the problem of explaining the why-not questions has received very little attention. There are currently two explanation models proposed for why-not questions. The first model explains a missing tuple t in terms of modifications to the database such that t appears in the query result wrt the modified database. The second model explains by identifying the data manipulatio...

• Type: Journal
• Year: 2010
• Where: SIGMOD
• Authors: Quoc Trung Tran, Chee-Yong Chan
• Keywords: Database, SIGMOD 2010, Tuples, Why-not Question