Programming Constructs for Unstructured Data

Peter Buneman, Susan Davidson, Dan Suciu

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We investigate languages for querying and transforming unstructured data by which we mean languages than can be used without knowledge of the structure (schema) of the database. There are two reasons for wanting to do this. First, some data models have emerged in which the schema is either completely absent or only provides weak constraints on the data. Second, it is sometimes convenient, for the purposes of browsing, to query the database without reference to the schema. For example one may want to "grep" all character strings in the database, or one might want to find the information associated with a certain field name no matter where it occurs in the database.

This paper introduces a labelled tree model of data and investigates various programming structures for querying and transforming such data. In particular, it considers various restrictions of structural recursion that give rise to well-defined queries even when the input data contains cycles. It also discusses issues of observable equivalence of such structures.
Original languageEnglish
Title of host publicationDatabase Programming Languages (DBPL-5)
Subtitle of host publicationProceedings of the Fifth International Workshop on Database Programming Languages, Gubbio, Umbria, Italy, 6-8 September 1995
PublisherSpringer-Verlag GmbH
Number of pages12
ISBN (Print)3-540-76086-5
Publication statusPublished - 1995


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