Thanks again Ivan With some tinkering I was able to achieve the behavior I was after using big:rdf_make_iid_of_qname() with a DELETE query
This won't work in all cases but should work for the common cases. Cheers, Rob On 6/1/12 3:43 PM, "Rob Vesse" <rve...@vdesign-studios.com> wrote: >Thanks Ivan that looks really helpful if somewhat tacky > >Most of the time I expect the triples that wants deleting will have been >very recently retrieved from Virtuoso itself so it's likely I can modify >my code to keep the original nodeID IRIs around and use those to look up >the internal Ids. In fact this may not require much modification since I >believe I just take the nodeID IRIs and use the portion after the // as >the blank node identifier for generated blank nodes anyway. > >I'll do some experiments and report back. > >Thanks, > >Rob > > >On 6/1/12 2:28 PM, "Ivan Mikhailov" <imikhai...@openlinksw.com> wrote: > >>Hello Rob, >> >>Two ways to refer to a particular blank node are to refer to it via some >>properties or to convert it to it's internal "serial number", a long >>integer, and back. >> >>--- Start from scratch. >>sparql clear graph <http://sample/> >> >>Done. -- 4 msec. >> >>--- Insert three blank nodes with two related triples each. >>sparql insert in graph <http://sample/> { [] <p> <o1a> , <o1b> . [] <p> >><o2a> , <o2b> . [] <p> <o3a> , <o3b> } >> >>Done. -- 15 msec. >> >>--- Delete one pair of triples. >>sparql with <http://sample/> delete { ?s ?p ?o } where { ?s ?p ?o ; <p> >><o1a> } >> >>Done. -- 7 msec. >> >>--- Ensure that we still have two bnodes, two triple per bnode. >>sparql select * from <http://sample/> where { ?s ?p ?o } >>s p o >>VARCHAR VARCHAR VARCHAR >>________________ >> >>nodeID://b10006 p o3a >>nodeID://b10006 p o3b >>nodeID://b10007 p o2a >>nodeID://b10007 p o2b >> >>4 Rows. -- 4 msec. >> >>--- Each bnode (as well as any "named" node) is identified internally as >>an integer >>sparql select (<LONG::bif:iri_id_num>(?s)) as ?s_num, ?p, ?o from >><http://sample/> where { ?s ?p ?o }; >>s_num p o >>INTEGER VARCHAR VARCHAR >>_____________________________ >> >>4611686018427397910 p o3a >>4611686018427397910 p o3b >>4611686018427397911 p o2a >>4611686018427397911 p o2b >> >>4 Rows. -- 5 msec. >> >>--- The integer can be converted back to internal identifier. Say, here >>we try to delete a triple that does not exist (even if the ID integer is >>valid) >>sparql delete from <http://sample/> >>{ `bif:iri_id_from_num(4611686018427397911)` <p> <o3a> }; >> >>Done. -- 5 msec. >> >>--- No effect, because 46..11 has <o2a> and <o2b>, not requested <o3a> >>sparql select * from <http://sample/> where { ?s ?p ?o }; >>s p o >>VARCHAR VARCHAR VARCHAR >>________________ >> >>nodeID://b10006 p o3a >>nodeID://b10006 p o3b >>nodeID://b10007 p o2a >>nodeID://b10007 p o2b >> >>4 Rows. -- 5 msec. >> >>--- Now let's try to delete a triple that does actually exist. Note the >>use of backquotes to insert an expression into template. >>sparql delete from <http://sample/> >>{ `bif:iri_id_from_num(4611686018427397911)` <p> <o2a> }; >> >>Done. -- 4 msec. >> >>--- So there's an effect >>sparql select * from <http://sample/> where { ?s ?p ?o }; >>s p o >>VARCHAR VARCHAR VARCHAR >>_________________ >> >>nodeID://b10006 p o3a >>nodeID://b10006 p o3b >>nodeID://b10007 p o2b >> >>3 Rows. -- 2 msec. >> >>--- Now delete everything related to nodeID://b10006 subject. >>sparql with <http://sample/> delete { ?s ?p ?o } where { ?s ?p ?o . >>filter (?s = bif:iri_id_from_num(4611686018427397910)) }; >> >>Done. -- 18 msec. >> >>--- Three minus two gives one triple remaining. >>SQL> sparql select * from <http://sample/> where { ?s ?p ?o }; >>s p o >>VARCHAR VARCHAR VARCHAR >>_________________ >> >>nodeID://b10007 p o2b >> >>1 Rows. -- 4 msec. >> >>IDs of bnodes will vary from server to server and even from run to run >>in same server, so the application should identify bnodes by properties >>before doing bif:iri_id_XXX tricks. >> >>Best Regards, >> >>Ivan Mikhailov >>OpenLink Software >>http://virtuoso.openlinksw.com >> > >
