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SPARQLing Constraints

This document outlines the motivations and preliminary approaches for utilizing SPARQL as a constraint language to manage relational database translation into RDF. It highlights the shortcomings of existing methods that overlook relational constraints such as primary and foreign keys. Three approaches are proposed: a naive method that loses constraint information, a modified approach that employs URIs for better representation, and a third approach that explicitly defines key and foreign key information using an extended RDF vocabulary. The satisfiability of various constraints is also discussed.

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SPARQLing Constraints

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  1. SPARQLing Constraints Ming Fang 07/31/2009

  2. Outlines • Motivation • Preliminary • Three Approaches • SPARKLing Constraints

  3. Motivation • Large amounts of data reside relational databases. • Existing approaches to translating relational data into RDF mostly disregard relational constraints • SPARQL can be used as a constraint language to check primary key, foreign key, etc.

  4. Preliminary • Key and foreign key • An RDF vocabulary V = (NC ,NP ), where NC is a finite set of classes and NP is a finite set of properties

  5. Three Approaches • Naïve approach

  6. Three Approaches • Naïve approach • Information about key and foreign key constraints is completely lost

  7. Three Approaches • Modified approach • Instead of using literals, we should use URIs from the object domain to represent keys and foreign keys • URIs appear only once; foreign key and corresponding key node collapse

  8. Three Approaches • The third approach • Key and FK information should be stated explicitly • Extend RDF vocabulary by a new namespace: rdfc • rdfc:Key, rdfc:Fkey, rdfc:ref • Keys and FKs may be built out of several components which are of type rdf:bag

  9. Three Approaches • The third approach

  10. Satifiability • Satisfiability of cardinality constraints, subproperty-chain and singleton constraints are undecidable. • Satisfiability of subclass, subproperty, property domain and property range, min- and max-cardinality, as well as unary foreign key and unary key constraints can be decided in ExpTime.

  11. SPARQLing Constraints • Extract constraints

  12. SPARQLing Constraints • Checking constraint violation • Key constraints

  13. SPARQLing Constraints • Checking constraint violation • Foreign key constraints • (i) there is an object of C that does not reference an object of D through p1…pn • (ii) the referenced properties do not constitute a key

  14. SPARQLing Constraints • Checking constraint violation • Cardinality constraints Max(c,n,p): Min (c,n,p):

  15. SPARQLing Constraints • Checking constraint violation • SubProperty-chain constraints

  16. SPARQLing Constraints • Checking constraint violation • Singleton constraints

  17. SPARQLing Constraints • Checking constraint violation • Anti-key constraints

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