Relational Technologies, Metadata and RDF [chapter]

Yannis Velegrakis
2009 Semantic Web Information Management  
Metadata plays an important role in successfully understanding and querying data on the web. A number of metadata management solutions have already been developed but each is tailored to specific kinds of metadata. The Resource Description Framework (RDF) is a generic, flexible and powerful model which is becoming the de-facto standard for metadata representation on the Web. Its adoption has created an exponential growth of the amount of available RDF data calling for efficient management
more » ... ons. Instead of designing such solutions from scratch, it is possible to invest on existing relational technologies by exploiting their long presence and maturity. Relational technologies can offer efficient storage and high performance querying at relatively low cost. Unfortunately, the principles of the relational model are fundamentally different from those of RDF. This difference means that specialized storage and querying schemes need to be put in place in order to use relational technologies for RDF data. In this work we provide a comprehensive description of these relational RDF storage schemes and discuss their advantages and limitations. We believe that through carefully designed schemes, it is possible to achieve sophisticated high performance systems that support the full power of RDF and bring one step closer the materialization of the Semantic Web vision. Yannis Velegrakis Metadata Approach Annotations [21] Atomic value annotations attached to a block of values within a tuple. They accompany the values as retrieved. Relational algebra query language. Provenance [11] Atomic data values carry their provenance, which propagates with them as they are retrieved. Query language supports predicates on provenance. Quality Parameters [28] Data values are associated with quality parameters (accuracy, freshness, etc.). SQL is extended to retrieve data using these parameters. Schema & Mappings [41, 47] Explicit modeling of schema and mapping information, and associations of it with portions of the data. SQL extension to retrieve data and metadata that satisfy certain metadata properties. Security [7] Credential-based access control. System reads complex security profiles and returns data results accordingly. Super-imposed Information [26]
doi:10.1007/978-3-642-04329-1_4 fatcat:zbofa7xavrfv5mgb3picv42lpe