Data exchange: semantics and query answering

Fagin, Ronald; Kolaitis, Phokion G.; Miller, Renée J.; Popa, Lucian

doi:10.1016/j.tcs.2004.10.033

Cited by 660 publications

(467 citation statements)

References 13 publications

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“…Skolem terms are used to relate target expressions across different SO tgds. An SO tgd without a Skolem term may also be called, simply, a tuple-generating dependency or tgd [8].…”

Section: Schema Mappings a Schema Mapping Is A Triple (S T σ)mentioning

confidence: 99%

“…The semantics that we adopt for a schema mapping (S, T, Σ) is the standard data exchange semantics [8] where, given a source instance I , the result of "executing" the mapping is the target instance J that is obtained by chasing I with the dependencies in Σ. Since the dependencies in Σ are SO tgds, we actually use an extension of the chase as defined in [9].…”

Section: Schema Mappings a Schema Mapping Is A Triple (S T σ)mentioning

confidence: 99%

“…One of the main steps in the integration or exchange of data is to design the mappings that describe the desired relationships between the various source schemas or source formats and the target schema. Once the mappings are established, they can be used either to support query answering on the (virtual) target schema, a process that is traditionally called data integration [14], or to physically transform the source data into the target format, a process referred to as data exchange [8]. In this paper, we focus on the data exchange aspect although our mapping generation methods will be equally applicable to derive mappings for data integration.…”

Section: Introductionmentioning

confidence: 99%

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MapMerge: correlating independent schema mappings

et al. 2012

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One of the main steps toward integration or exchange of data is to design the mappings that describe the (often complex) relationships between the source schemas or formats and the desired target schema. In this paper, we introduce a new operator, called MapMerge, that can be used to correlate multiple, independently designed schema mappings of smaller scope into larger schema mappings. This allows a more modular construction of complex mappings from various types of smaller mappings such as schema correspondences produced by a schema matcher or pre-existing mappings that were designed by either a human user or via mapping tools. In particular, the new operator also enables a new "divide-and-merge" paradigm for mapping creation, where the design is divided (on purpose) into smaller components that are easier to create and understand and where MapMerge is used to automatically generate a meaningful overall mapping. We describe our MapMerge algorithm and demonstrate the feasibility of our implementation on several real and synthetic mapping scenarios. In our experiments, we make use of a novel similarity measure between two database instances with different schemas that quantifies the preservation of data associations. We show experimentally that MapMerge improves the quality of the schema mappings, by significantly increasing the similarity between the input source instance and the generated target instance. Finally, we provide a new algorithm that combines MapMerge with schema mapping composition to correlate flows of schema mappings.

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“…Skolem terms are used to relate target expressions across different SO tgds. An SO tgd without a Skolem term may also be called, simply, a tuple-generating dependency or tgd [8].…”

Section: Schema Mappings a Schema Mapping Is A Triple (S T σ)mentioning

confidence: 99%

Section: Schema Mappings a Schema Mapping Is A Triple (S T σ)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

MapMerge: correlating independent schema mappings

et al. 2012

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“…In some ways, the construction given above is similar to the construction of the universal solutions of [16,Definition 2.4], in that both are based upon similar notions of endomorphism (there termed homomorphism). However, those universal solutions are not required to be tuple minimal.…”

Section: Definition 18 (Representation Of ∃∧+-Sentences As Sets Of D-mentioning

confidence: 99%

“…In [16,Definition 3.7], the notion of a weakly acyclic set of TGDs is developed, and it is shown [16,Theorem 3.9] that the chase procedure always terminates when the dependencies are limited to an acyclic set of of TGDs together with EGDs. The TGDs and EGDs of [16] differ only in relatively minor ways from the TGHDs and EGHDs of this paper; in particular, the result extends directly to TGDs. The details will not be worked out, but the following result is noted for completeness.…”

Section: Theorem 32 (Conditional Existence Of Canonical Models) If Comentioning

confidence: 99%

Information-based distance measures and the canonical reflection of view updates

Hegner

2011

Ann Math Artif Intell

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For the problem of reflecting an update on a database view to the main schema, the constant-complement strategies are precisely those which avoid all update anomalies, and so define the gold standard for well-behaved solutions to the problem. However, the families of view updates which are supported under such strategies are limited, so it is sometimes necessary to go beyond them, albeit in a systematic fashion. In this work, an investigation of such extended strategies is initiated for relational schemata. The approach is to characterize the information content of a database instance, and then require that the optimal reflection of a view update to the main schema embody the least possible change of information.The key property is identified to be strong monotonicity of the view, meaning that view insertions may always be reflected as insertions to the main schema, and likewise for deletions. In that context it is shown that for insertions and deletions, an optimal update, entailing the least change of information, exists and is unique up to isomorphism for wide classes of constraints.

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A visual XML dataspace approach for satisfying ad hoc information needs

Moilanen

Niemi

Näppilä

et al. 2015

Asso for Info Science & Tech

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Dataspace systems constitute a recent data management approach that supports better cooperation among autonomous and heterogeneous data sources with which the user is initially unfamiliar. A central idea is to gradually increase the user's knowledge about the contents, structures, and semantics of the data sources in the dataspace. Without this knowledge, the user is not able to make sophisticated queries. The dataspace systems proposed so far are usually application specific. In contrast, our idea in this paper is to develop an application-independent extensible markup language (XML) dataspace system with versatile facilities. Unlike the other proposed dataspace systems, we show that it is possible to build an interface based on conventional visual tools in terms of which the user can satisfy his or her sophisticated information needs. In our system, the user does not need to master programming techniques nor the XML syntax, which provides a good starting point for its declarative use.

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Data exchange: semantics and query answering

Cited by 660 publications

References 13 publications

MapMerge: correlating independent schema mappings

MapMerge: correlating independent schema mappings

Information-based distance measures and the canonical reflection of view updates

A visual XML dataspace approach for satisfying ad hoc information needs

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