Storing and querying tree-structured records in Dremel

Storing and Querying Tree-Structured Records in Dremel

In Dremel, data is stored as nested relations. The schema for a relation is a tree, all of whose nodes are attributes, and whose leaf attributes hold values. We explore filter and aggregate queries that are given in the Dremel dialect of SQL. Complications arise because of repeated attributes, i.e., attributes that are allowed to have more than one value. We focus on the common class of Dremel ...

Querying Tree-Structured Data Using Dimension Graphs

Tree structures provide a popular means to organize the information on the Web. Taxonomies of thematic categories, concept hierarchies, e-commerce product catalogs are examples of such structures. Querying multiple data sources that use tree structures to organize their data is a challenging issue due to name mismatches, structural differences and structural inconsistencies that occur in such s...

Storing and Querying RDF Data in Atlas∗

Storing and Querying Ontologies in Logic Databases

The intersection of Description Logic inspired ontology languages with Logic Programs has been recently analyzed in [GHVD03]. The resulting language, called Description Logic Programs, covers RDF Schema and a notable portion of OWL Lite. However, the proposed mapping in [GHVD03] from the corresponding OWL fragment into Logic Programs has shown scalability as well as representational deficits wi...

Storing and querying large XML instances

After its introduction in 1998, XML has quickly emerged as the de facto exchange format for textual data. Only ten years later, the amount of information that is being processed day by day, locally and globally, has virtually exploded, and no end is in sight. Correspondingly, many XML documents and collections have become much too large for being retrieved in their raw form – and this is where ...