Tableau Techniques for Querying Information Sources through Global Schemas

Grahne, Gösta; Mendelzon, Alberto O.

doi:10.1007/3-540-49257-7_21

Cited by 101 publications

(84 citation statements)

References 13 publications

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“…[50]), the use of global schema (e.g. [25]), and conceptual modelling for information integration based on description logics [9,8,23,51,2]. These differ from our approach in that they do not seek an automated approach that uses domain knowledge for identifying and acting on inconsistencies.…”

Section: Discussionmentioning

confidence: 98%

Fusion rules for merging uncertain information

Hunter

Liu

2006

Information Fusion

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In previous papers, we have presented a logic-based framework based on fusion rules for merging structured news reports. Structured news reports are XML documents, where the textentries are restricted to individual words or simple phrases, such as names and domain-specific terminology, and numbers and units. We assume structured news reports do not require natural language processing. Fusion rules are a form of scripting language that define how structured news reports should be merged. The antecedent of a fusion rule is a call to investigate the information in the structured news reports and the background knowledge, and the consequent of a fusion rule is a formula specifying an action to be undertaken to form a merged report. It is expected that a set of fusion rules is defined for any given application. In this paper we extend the approach to handling probability values, degrees of beliefs, or necessity measures associated with textentries in the news reports. We present the formal definition for each of these types of uncertainty and explain how they can be handled using fusion rules. We also discuss the methods of detecting inconsistencies among sources.

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Section: Discussionmentioning

confidence: 98%

Fusion rules for merging uncertain information

Hunter

Liu

2006

Information Fusion

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“…Potential type incompatibilities can be resolved through type transformation functions. Other types of mappings include complete (Q S ⊇ Q T ) and exact (Q S =Q T ) mappings [8]. Note that although the queries are restricted to return sets of tuples, the schemas may be nested schemas and may contain complex or abstract types.…”

Section: Mapping Systemmentioning

confidence: 99%

Mapping Adaptation under Evolving Schemas

Velegrakis

Miller

Popa

2003

Proceedings 2003 VLDB Conference

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To achieve interoperability, modern information systems and e-commerce applications use mappings to translate data from one representation to another. In dynamic environments like the Web, data sources may change not only their data but also their schemas, their semantics, and their query capabilities. Such changes must be reflected in the mappings. Mappings left inconsistent by a schema change have to be detected and updated. As large, complicated schemas become more prevalent, and as data is reused in more applications, manually maintaining mappings (even simple mappings like view definitions) is becoming impractical. We present a novel framework and a tool (ToMAS) for automatically adapting mappings as schemas evolve. Our approach considers not only local changes to a schema, but also changes that may affect and transform many components of a schema. We consider a comprehensive class of mappings for relational and XML schemas with choice types and (nested) constraints. Our algorithm detects mappings affected by a structural or constraint change and generates all the rewritings that are consistent with the semantics of the mapped schemas. Our approach explicitly models mapping choices made by a user and maintains these choices, whenever possible, as the schemas and mappings evolve. We describe an implementation of a mapping management and adaptation tool based on these ideas and compare it with a mapping generation tool.

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“…The assertions in the mapping establish the connection between the relations of the global schema and those of the source schema. As typical in data integration, we consider here mappings that are sound, i.e., the data provided by the queries over the sources satisfy the queries over the global schema, but do not necessarily characterize completely the answer of the queries over the global schema [16,9,7]. User queries are posed over the global schema and are answered by retrieving data from the sources, making use of the mapping.…”

Section: It Holds That T[a] = T[a ] a Single Head Full Dependencymentioning

confidence: 99%

“…It is also well known that processing queries in the LAV approach is a difficult task [15,16,8,1,7,3,4]. Indeed, in this approach, the only knowledge we have about the data in the global schema is through the views representing the sources, and such views provide only partial information about the data.…”

Section: Introductionmentioning

confidence: 99%

On the Expressive Power of Data Integration Systems

Calì¹,

Calvanese²,

Giacomo³

et al. 2002

Conceptual Modeling — ER 2002

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Abstract. There are basically two approaches for designing a data integration system. In the global-as-view (GAV) approach, one maps the concepts in the global schema to views over the sources, whereas in the local-as-view (LAV) approach, one maps the sources into views over the global schema. The goal of this paper is to relate the two approaches with respect to their expressive power. The analysis is carried out in a relational database setting, where both the queries on the global schema, and the views in the mapping are conjunctive queries. We introduce the notion of query-preserving transformation, and query-reducibility between data integration systems, and we show that, when no integrity constraints are allowed in global schema, the LAV and the GAV approaches are incomparable. We then consider the addition of integrity constraints in the global schema, and present techniques for query-preserving transformations in both directions. Finally, we show that our results imply that we can always transform any system following the GLAV approach (a generalization of both LAV and GAV) into a query-preserving GAV system.

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Tableau Techniques for Querying Information Sources through Global Schemas

Cited by 101 publications

References 13 publications

Fusion rules for merging uncertain information

Fusion rules for merging uncertain information

Mapping Adaptation under Evolving Schemas

On the Expressive Power of Data Integration Systems

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