The VLDB Journal

, Volume 25, Issue 4, pp 597–622

A holistic and principled approach for the empty-answer problem

  • Davide Mottin
  • Alice Marascu
  • Senjuti Basu Roy
  • Gautam Das
  • Themis Palpanas
  • Yannis Velegrakis
Regular Paper

DOI: 10.1007/s00778-016-0431-8

Cite this article as:
Mottin, D., Marascu, A., Roy, S.B. et al. The VLDB Journal (2016) 25: 597. doi:10.1007/s00778-016-0431-8


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.


Database Database usability Query modification Empty-answer problem 

Funding information

Funder NameGrant NumberFunding Note
National Science Foundation
  • 0812601
  • 0915834
National Science Foundation
  • 1018865

Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Hasso Plattner InstitutePotsdamGermany
  2. 2.University of TrentoTrentoItaly
  3. 3.IBM Research-IrelandDublinIreland
  4. 4.Department of Computer ScienceNew Jersey Institute of TechnologyNewarkUSA
  5. 5.University of Texas ArlingtonArlingtonUSA
  6. 6.QCRIDohaQatar
  7. 7.University of Paris DescartesParisFrance

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