A holistic and principled approach for the empty-answer problem

Davide Mottin*, Alice Marascu, Senjuti Basu Roy, Gautam Das, Themis Palpanas, Yannis Velegrakis

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


We propose a principled optimization-based interactive query relaxation framework for queries that return no answers. Given an initial query that returns an empty-answer set, our framework dynamically computes and suggests alternative queries with fewer conditions than those the user has initially requested, in order to help the user arrive at a query with a non-empty-answer, or at a query for which no matter how many additional conditions are ignored, the answer will still be empty. Our proposed approach for suggesting query relaxations is driven by a novel probabilistic framework based on optimizing a wide variety of application-dependent objective functions. We describe optimal and approximate solutions of different optimization problems using the framework. Moreover, we discuss two important extensions to the base framework: the specification of a minimum size on the number of results returned by a relaxed query and the possibility of proposing multiple conditions at the same time. We analyze the proposed solutions, experimentally verify their efficiency and effectiveness, and illustrate their advantages over the existing approaches.

Original languageEnglish
Pages (from-to)597-622
Number of pages26
JournalVLDB Journal
Issue number4
Publication statusPublished - 1 Aug 2016


  • Database
  • Database usability
  • Empty-answer problem
  • Query modification


Dive into the research topics of 'A holistic and principled approach for the empty-answer problem'. Together they form a unique fingerprint.

Cite this