Equivalence of queries combining set and bag-set semantics

Sara Cohen*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

21 Scopus citations

Abstract

The query equivalence problem has been studied extensively for set-semantics and, more recently, for bag-set semantics. However, SQL queries often combine set and bag-set semantics. For example, an SQL query that returns a multiset of elements may call a ubquery or view that returns a set of elements. As another example, in SQL one can compute a multiset-union of queries, each of which returns a set of answers. This paper presents combined semantics, which formally models query evaluation combining set and bag-set semantics. The equivalence problem for queries evaluated under combined semantics is studied. A sufficient condition for equivalence is presented. For several important common classes of queries necessary and sufficient conditions for equivalence are presented.

Original languageEnglish
Title of host publicationProceedings of the Twenty-Fifth ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems, PODS 2006
Pages70-79
Number of pages10
DOIs
StatePublished - 2006
Externally publishedYes
Event25th ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems, PODS 2006 - Chicago, IL, United States
Duration: 26 Jun 200628 Jun 2006

Publication series

NameProceedings of the ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems

Conference

Conference25th ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems, PODS 2006
Country/TerritoryUnited States
CityChicago, IL
Period26/06/0628/06/06

Keywords

  • Bag semantics
  • Combined semantics
  • Datalog
  • Query equivalence
  • Set semantics

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