GraphDB-SE Query Behaviour

compared with
Current by Vladimir Alexiev
on Dec 13, 2014 16:00.

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There are several more special graph URIs used in GraphDB-SE, which are used to control query evaluation.
|| Clause || Behaviour ||
| {{FROM/FROM NAMED <}}{{[http://www.ontotext.com/disable-sameAs]}}{{>}} | Switch off the enumeration of equivalence classes produced by the [owl:sameAs Optimisation|GraphDB-SE Reasoner#sameAs Optimisation]. By default, all owl:sameAs URIs are returned by triple pattern matching. E.g. if a triple matches the pattern {{ex:Inst rdf:type ex:Class}} and {{ex:Inst}} is {{owl:sameAs}} to {{ex:Inst2}} then by default 2 triples are returned, one for {{ex:Inst}} and another for {{ex:Inst2}}. The purpose of this clause is to reduce the number of results to include a single representative from each owl:sameAs class. BE AWARE that if the query uses filters over the textual representation of a URI, then this clause may skip some valid solutions since not all the nodes within an equivalence class will be matched against such a {{FILTER}}. |
| {{FROM/FROM NAMED <}}{{[http://www.ontotext.com/disable-sameAs]}}{{>}} | Switch off the enumeration of equivalence classes produced by the [owl:sameAs Optimisation|GraphDB-SE Reasoner#sameAs Optimisation]. By default, all owl:sameAs URIs are returned by triple pattern matching. This clause reduces the number of results to include a single representative from each owl:sameAs class. See [Not enumerating sameAs|GraphDB-SE Performance Tuning#Not enumerating sameAs] for details|
| {{FROM/FROM NAMED <}}{{[http://www.ontotext.com/count]}}{{>}} | Used to trigger the evaluation of the query, so that it gives a single result in which all the variable bindings in the projection are replaced with a plain literal, holding the value of the total number of solutions of the query. In the case of a CONSTRUCT query in which the projection contains three variables (?subject, ?predicate, ?object), the subject and the predicate are bound to {{<}}{{[http://www.ontotext.com/]}}{{>}} and the object holds the literal value; this is because there cannot exist a statement with literal in the place of the subject or predicate. This clause is deprecated in favor of using the COUNT aggregate of SPARQL 1.1|
| {{FROM/FROM NAMED <}}{{[http://www.ontotext.com/skip-redundant-implicit]}}{{>}} | Used to trigger the exclusion of implicit statements when there exists an explicit one within a specific context(even default). Initially implemented to allow for filtering of redundant rows where the context part is not taken into account and which leads to 'duplicate' results. |