Special Issue on the 2018 International Conference on Database Theory

This volume is dedicated to invited papers from the 21st edition of the International Conference on Database Theory (ICDT 2018). The conference was held in Vienna, Austria on March 26–29, 2018. Originally biennial, the ICDTconference has been held annually and jointly with the conference on Extending Database Technology (EDBT) since 2009. The Program Committee of ICDT 2018 has selected the papers invited to the special issue with the goal of highlighting top contributions from the conference. The invited papers were further reviewed according to the journal’s rigorous peer-review standards. The four selected papers represent different viewpoints, and contribute significant insights, on the fundamental challenge of query evaluation over databases.