Path Constraints in Semistructured Databases

Buneman, Peter; Fan, Wenfei; Weinstein, Scott

doi:10.1006/jcss.2000.1710

Cited by 45 publications

(46 citation statements)

References 28 publications

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“…Figure 2.1 (a) shows an XML document storing information about provinces in Canada and conforming to the DTD shown in Example 2.2. 6 , @inProvince) = Manitoba 2 Our model is simpler than the models of XQuery and XML Schema as DTDs support only one basic type (PCDATA or string) and do not have complex type constructs. Unlike the data model of XQuery, we do not consider nodes representing namespaces, processing instructions and references.…”

Section: V N ] and The String Lab(v 1 ) · · · Lab(v N ) Is In Thmentioning

confidence: 99%

On the Complexity of Verifying Consistency of XML Specifications

Arenas¹,

Fan²,

Libkin³

2008

SIAM J. Comput.

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Abstract. XML specifications often consist of a type definition (typically, a DTD) and a set of integrity constraints. It has been shown previously that such specifications can be inconsistent, and thus it is often desirable to check consistency at compile-time. It is known [16] that for general keys and foreign keys, and DTDs, the consistency problem is undecidable; however, it becomes NP-complete when all keys are one-attribute (unary), and tractable, if no foreign keys are used.In this paper, we consider a variety of previously studied constraints for XML data, and investigate the complexity of the consistency problem. Our main conclusion is that in the presence of foreign key constraints, compile-time verification of consistency is infeasible. We look at absolute constraints that hold in the entire document, and relative constraints that only hold in a part of the document. For absolute constraints, we prove decidability and establish complexity bounds for primary multi-attribute keys and unary foreign keys, and study unary constraints that involve regular expressions. For relative constraints, we prove that even for unary constraints, the consistency problem is undecidable. We also show that results continue to hold for extended DTDs, a more expressive typing mechanism for XML.1. Introduction. XML data, just like relational and object-oriented data, can be specified in a certain data definition language. While the exact details of XML data definition languages are still being worked out, it is clear that all of them would contain a form of document description, as well as integrity constraints. Constraints are naturally introduced when one considers transformations between XML and relational databases [10,12,18,19,23,30,31], as well as integrating several XML documents [2,3,4,15]. Document descriptions usually come in the form of DTDs (Document Type Definition), and constraints are typically natural analogs of the most common relational integrity constraints: keys and foreign keys. Indeed, a large number of proposals (e.g., [35,38,36,5]) support specifications for keys and foreign keys.We investigate XML specifications with DTDs and keys and foreign keys. We study the consistency, or satisfiability, of such specifications: given a DTD and a set of constraints, whether there are XML documents conforming to the DTD and satisfying the constraints. In other words, we want to validate XML specifications statically, at compile-time. Invalid XML specifications are likely to be more common than invalid specifications of other kinds of data, due to the rather complex interaction of DTDs and constraints. Furthermore, many specifications are not written at once, but rather in stages: as new requirements are discovered, they are added to the constraints, and thus it is quite possible that at some point they may be contradictory.An alternative to the static validation would be a dynamic approach: simply attempt to validate a document with respect to a DTD and a set of constraints. This, however, would not tell us whethe...

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Section: V N ] and The String Lab(v 1 ) · · · Lab(v N ) Is In Thmentioning

confidence: 99%

On the Complexity of Verifying Consistency of XML Specifications

Arenas¹,

Fan²,

Libkin³

2008

SIAM J. Comput.

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“…These constraints have been introduced by Abiteboul and Vianu in [3]. See for instance [8], [17] or [5] where different classes of path constraints are analyzed. Here, we study path inclusion constraints.…”

Section: This Research Was Partially Supported By Inria (Mostrare Team)mentioning

confidence: 99%

Extraction and Implication of Path Constraints

André

Caron

Debarbieux

et al. 2004

Lecture Notes in Computer Science

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Abstract. We consider semistructured data as rooted edge-labeled directed graphs, and path inclusion constraints on these graphs. In this paper, we show that we can extract from a finite datum D a finite set C f (D) of word inclusions, which implies exactly every word inclusion satisfied by D. Then, we give a new decision algorithm for the implication problem of a constraint p q by a set of constraints pi ui where p, q, and the pi's are regular path expressions and the ui's are non empty paths, improving in this particular case, the more general algorithms of S. Abiteboul and V. Vianu, and Alechina et al. Moreover, in the case of a set of word equalities ui ≡ vi, we give a more efficient decision algorithm for the implication of a word equality u ≡ v, improving the more general algorithm of P. Buneman et al., and we prove that, in this case, the implication problem for non deterministic models or for (complete) deterministic models are equivalent.

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“…Im Gegensatz zu unserem Ansatz kommt dem Einsatz entscheidbarer Logiken im Datenbankbereich eine hohe Bedeutung zu, z. B. in semi-strukturierten Datenbanken [9], Content-ManagementSystemen [14] oder Wissensdatenbanken [32]. Wir konzentrieren uns jedoch eher auf das präzise Aufzeigen von Inkonsistenzen in einer konkreten Spezifikation und nicht auf eine a-priori Konsistenzgarantie.…”

Section: Vergleich Mit Weiteren Ansätzen Zur Konsistenzüberwachungunclassified

Formale Konsistenzsicherung in informellen Software-Spezifikationen

Scheffczyk

Stutz

Borghoff

et al. 2004

Informatik Forsch. Entw.

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Zusammenfassung. Die Spezifikation ist die Grundlage für den Erfolg eines Software-Projekts. Der Praktiker konzentriert sich hier i. d. R. auf die größte Herausforderung: die vollständi-ge und inhaltlich korrekte Erfassung aller Anforderungen an das zu erstellende Software-System. Dass Spezifikationen für große Systeme aus vielen Dokumenten verschiedener Ausprägung in Form und Inhalt bestehen, tritt dabei meist in den Hintergrund. Ihre Konsistenz wird meist mit hohem manuellem Aufwand sichergestellt. Der Erstellung formal korrekter und konsistenter Software-Spezifikationen widmen sich zahlreiche theoretische Arbeiten. In der Praxis sind sie jedoch meist nicht mit der gewohnten Arbeitsweise vereinbar. In diesem Artikel stellen wir einen Mittelweg vor: Wir nutzen die Spezifikationsbausteine von sd&m für die Spezifikation, die als Ergebnisse Dokumente in natürlicher Sprache sowie semiformale Darstellungen umfasst. Für Spezifikationen, die nach diesen Bausteinen erstellt wurden, definieren wir Konsistenz durch formale zeitbehaftete Konsistenzregeln. Ein von uns entwickeltes Auswertungswerkzeug ermittelt Inkonsistenzen präzise. Unterstützt von einem solchen Werkzeug kann sich der Software-Ingenieur wieder ganz auf das Hauptanliegen der Spezifikation konzentrieren: ihre inhaltliche Korrektheit und Vollständigkeit.Abstract. Specification is the base for the success of a software project. Usually, practitioners concentrate on completely and correctly capturing all requirements for the specified system. In practice, a serious problem often fails to gain attention: Specifications for large systems consist of many documents with heterogeneous structure and content. Their consistency is often achieved by time-consuming manual effort. On the other hand, many theoretical approaches aim at formally correct and consistent software specifications. In practice, however, these approaches fail to be integrated into the every day work of software engineers. This article is located at the boundary between theory and practice: For specifying software we use analysis modules developed at sd&m, the results of which are documents in natural language or semi-formal documents. For a specification using our analysis modules we define consistency via formal temporal consistency rules. Our newly developed tool pinpoints inconsistencies precisely. Supported by our tool, software designers can concentrate on their actual work: the technical correctness and completeness of a specification.

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Path Constraints in Semistructured Databases

Cited by 45 publications

References 28 publications

On the Complexity of Verifying Consistency of XML Specifications

On the Complexity of Verifying Consistency of XML Specifications

Extraction and Implication of Path Constraints

Formale Konsistenzsicherung in informellen Software-Spezifikationen

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