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 languageAmerican English
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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