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Table of Contents
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Common Questions
- Can queries be done across triplestores? The original plan was to reference an external URI for bibliographic references (e.g.,
http://da-rdf.library.cornell.edu/individual/b3652730) and not copy any information about the bibliographic reference into our local triplestore. The requirement to sort by title, author, and publication date with you to require that this information be copied into the local triplestore, or that the SPARQL queries are capable of querying across two distinct triplestores. - How does SPARQL handle sorting?
- How does SPARQL track paginated results? How does SPARQL track tokens for retrieving the next set of search results?
- Missing Triples for an 'object' -- From the SPARQL doc, it appears that if any one of the 'objects' (e.g., title, description, size, visibility) listed in the WHERE of the query is not defined for a virtual collection, then that virtual collection will not be included in the results. I have not tested this. Is there a way around this limitation? I'd like the value for the missing object to be _BLANK_ or nil.
Example from SPARQL doc
Data:
Code Block language none @prefix foaf: <http://xmlns.com/foaf/0.1/> . _:a foaf:name "Johnny Lee Outlaw" . _:a foaf:mbox <mailto:jlow@example.com> . _:b foaf:name "Peter Goodguy" . _:b foaf:mbox <mailto:peter@example.org> . _:c foaf:mbox <mailto:carol@example.org> .
Query:
Code Block language none PREFIX foaf: <http://xmlns.com/foaf/0.1/> SELECT ?name ?mbox WHERE { ?x foaf:name ?name . ?x foaf:mbox ?mbox }Query Result:
name mbox "Johnny Lee Outlaw" <mailto:jlow@example.com> "Peter Goodguy" <mailto:peter@example.org> Question:
- Why isn't mbox=<mailto:carol@example.org> part of the result with name=_BLANK_?
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