- From: Ashok Malhotra <ashok.malhotra@oracle.com>
- Date: Tue, 17 Sep 2013 16:58:54 -0400
- To: vladimir.alexiev@ontotext.com
- CC: public-rdb2rdf-comments@w3.org, "'Gregg Garcia'" <GGarcia@getty.edu>
Thanks, Vladimir! I will file this suggestion and we can look at it if we reopen the WG. All the best, Ashok On 9/17/2013 4:03 PM, Vladimir Alexiev wrote: > 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 20:59:58 UTC