- From: Vladimir Alexiev <vladimir.alexiev@ontotext.com>
- Date: Tue, 17 Sep 2013 23:03:20 +0300
- To: <public-rdb2rdf-comments@w3.org>
- Cc: "'Gregg Garcia'" <GGarcia@getty.edu>
Hi everyone! If a column value (or any of the columns in a rr:template) is null, an r2rml processor should skip the involved triple. If the rr:subjectMap column is null, it should skip all triples in that rr:TriplesMap. This is especially important since R2RML doesn't offer any conditionals. This behaviour is stated quite definitely at: http://www.w3.org/2001/sw/rdb2rdf/wiki/RDBNullValues#R2RML 1. But IMHO the R2RML spec is silent on what happens when a subjectMap or objectMap is null. If we read pedantically: "A predicate-object map is a function that creates *one* or more predicate-object pairs for each logical table row" then it should generate a triple with null. Please add some langauge to the effect of the above wiki page. 2. Please also add conformance tests with NULLs. E.g. the perl module RDF::RDB2RDF does NOT ignore nulls, even though it's passed the conformance test. Thanks! -- Vladimir Alexiev, PhD, PMP Lead, Data and Ontology Management Group Ontotext Corp, www.ontotext.com Sirma Group Holding, www.sirma.com Email: vladimir.alexiev@ontotext.com, skype:valexiev1 Mobile: +359 888 568 132, SMS: 359888568132@sms.mtel.net Landline: +359 (988) 106 084, Fax: +359 (2) 975 3226 Calendar: https://www.google.com/calendar/embed?src=vladimir%40sirma.bg
Received on Tuesday, 17 September 2013 20:03:49 UTC