A Semantics-Based Approach to Design of Query Languages for Partial Information

dc.contributor.authorLibkin, Leonid
dc.date2023-05-17T00:58:41.000
dc.date.accessioned2023-05-22T12:53:46Z
dc.date.available2023-05-22T12:53:46Z
dc.date.issued1994
dc.date.submitted2007-07-10T10:42:34-07:00
dc.description.abstractMost of work on partial information in databases asks which operations of standard languages, like relational algebra, can still be performed correctly in the presence of nulls. In this paper a different point of view is advocated. We believe that the semantics of partiality must be clearly understood and it should give us new design principles for languages for databases with partial information. There are different sources of partial information, such as missing information and conflicts that occur when different databases are merged. In this paper, we develop a common semantic framework for them which can be applied in a context more general than the flat relational model. This ordered semantics, which is based on ideas used in the semantics of programming languages, cleanly intergrates all kinds of partial information and serves as a tool to establish connections between them. Analyzing properties of semantic domains of types suitable for representing partial information, we come up with operations that are naturally associated with those types, and we organize programming syntax around these operations. We show how the languages that we obtain can be used to ask typical queries about incomplete information in relational databases, and how they can express some previously proposed languages. Finally, we discuss a few related topics such as mixing traditional constraints with partial information and extending semantics and languages to accommodate bags and recursive types.
dc.description.commentsUniversity of Pennsylvania Department of Computer and Information Science Technical Report No. MS-CIS-94-38.
dc.identifier.urihttps://repository.upenn.edu/handle/20.500.14332/7133
dc.legacy.articleid1240
dc.legacy.fulltexturlhttps://repository.upenn.edu/cgi/viewcontent.cgi?article=1240&context=cis_reports&unstamped=1
dc.source.issue226
dc.source.journalTechnical Reports (CIS)
dc.source.statuspublished
dc.subject.otherpartial information in databass
dc.subject.othersemantics
dc.subject.othertypes
dc.subject.otherquery languages
dc.subject.otherdisunctive information
dc.subject.otherconstraints
dc.titleA Semantics-Based Approach to Design of Query Languages for Partial Information
dc.typeReport
digcom.contributor.authorLibkin, Leonid
digcom.identifiercis_reports/226
digcom.identifier.contextkey323285
digcom.identifier.submissionpathcis_reports/226
digcom.typereport
dspace.entity.typePublication
upenn.schoolDepartmentCenterTechnical Reports (CIS)
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