Can I Delete Triples containing Blank Nodes? There are two ways to delete a particular blank node: Refer to it indirectly, using some of its properties, or Discover and refer to it by its internal "serial number" or ID (in Virtuoso, bif:iri_id_XXX, a long integer). Important Note: IDs of bnodes will always vary from server to server, and often from run-to-run on the same server, so it is usually better to identify bnodes by properties than ID. How to Delete Triples containing Blank Nodes Assume the following sample scenario: Clear the graph: 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. Every node in the Virtuoso store, whether "named" or "blank" ("unnamed"), is identified internally by a long 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. Should have no effect, because the "46..11" IRI has <o2a> and <o2b>, and was 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 the graph template: SPARQL DELETE FROM <http://sample/> { `bif:iri_id_from_num(4611686018427397911)` <p> <o2a> }; Done. -- 4 msec. This time, 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 we'll 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. This should delete two of the previous three triples, leaving one remaining triple: SQL> SPARQL SELECT * FROM <http://sample/> WHERE { ?s ?p ?o }; s p o VARCHAR VARCHAR VARCHAR ___________________________________ nodeID://b10007 p o2b 1 Rows. -- 4 msec. Related Virtuoso Tips and Tricks Collection Virtuoso Documentation Deleting triples from a graph Deleting triples from a "Large" graph