Failing queries are database queries returning few o no results. It might be useful reformulating them in order to retrieve results that are close to those intended with original queries. In this paper, we introduce an approach for rewriting failing queries that are in the disjunctive normal form. In particular, the approach prescribes to replace some of the attributes of the failing queries with attributes semantically related to them by means of Relaxed Functional Dependencies (rfds), which can be automatically discovered from data. The semantics of automatically discovered rfds allow us to rank them in a way to provide an application order during the query rewriting process. Experiments show that such application order of rfds yields a ranking of the approximate query answers meeting the expectations of the user.
|Titolo:||Dependency-based Query Result Approximation|
|Data di pubblicazione:||2018|
|Appare nelle tipologie:||4.1 Contributi in Atti di convegno|