Proceedings of the 12th International Conference on Database Theory

The papers here were presented at the 12th International Conference on Database Theory (ICDT '09), held in St. Petersburg, Russia, March 23--25, 2009. Until this year, ICDT was held every two years, with the preceding ICDT being held in 2007. From now on, ICDT will be held annually. Beginning this year, ICDT is being held jointly with EDBT ("Extending Database Technology"). EDBT is being held on March 24--26, 2009. In response to a Call for Papers, 77 submissions were received by the submission deadline of August 14, 2008. All were submitted electronically through EasyChair. EasyChair was also used for the Program Committee deliberations, which were held completely electronically. The Program Committee selected 25 papers for presentation. The paper "Repair Checking in Inconsistent Databases: Algorithms and Complexity" by Foto Afrati and Phokion Kolaitis, was selected for the ICDT Best Paper Award. The paper "Containment of Conjunctive Queries on Annotated Relations", by Todd J. Green, was selected for the ICDT Best Student Paper Award. In addition, there are two Keynote Speakers: Georg Gottlob and Victor Vianu. Furthermore, Umesh Dayal is a Keynote Speaker for EDBT. The submissions were not formally refereed and many of these papers represent reports of continuing research. It is expected that most of them will appear in a more polished and complete form in scientific journals.