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Collation Sequences in SPARQL

The SPARQL query language is relatively silent about how to order strings. When the question was posed to us a while back, what to expect as the order of a solution sequence which contained string literals with language tags, we had just the conservative answer that the relation among simple or string literals and plain literals was undefined. This was not a nice situation.

Even though RDF 1.1 ratifies the type rdf:langString, it defines no relation beyond equality, which leaves plfn:compare to apply but requires some context where it is possible to determine the collation sequence. This situation is not quite as unpleasant, but still not satisfactory. Fortunately ‘undefined’ leaves latitude for improvement, by definition…

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Extended Temporal Datatype Support

Dydra recently extended its native support to cover the full XSD temporal data type complement. This means not only that our platform continues to provide compact native representations for the core data types:

  • xsd:date
  • xsd:dateTime
  • xsd:time

where each term requires one cell – that is, eight bytes, but, in addition, SPOCQ, Dydra’s SPARQL processor, implements internal data classes for the remaining types:

  • xsd:dayTimeDuration
  • xsd:yearMonthDuration
  • xsd:gDay
  • xsd:gMonth
  • xsd:gMonthDay
  • xsd:gYear
  • xsd:gYearMonth
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Quads with a View

The observant user may have noticed, that the controls in our query editor have ever so slightly changed. In particular, the list is no longer titled “Queries”. The header is “Views” and each entry has an additional icon: a link.

sparql_link

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