Hi to all
Recently I have sent two e-mails to this forum about two different problems:
- *Unable to iterate over a SPARQL query referring to a graph.* In a
stored procedure the iterations over a SPARQL statement result set are not
executed. See
https://sourceforge.net/p/virtuoso/mailman/message/35686416/
- *Unable to delete a graph content * Some graphs are impossible to
delete, despite the deletion commands do not issue any error. See
https://sourceforge.net/p/virtuoso/mailman/message/35655255/
Now I have found that they are related. Both happen *only *with RDF graphs
which content is generated with the R2RML mapping feature using the
procedures DB.DBA.TTLP() and DB.DBA.R2RML_MAKE_QM_FROM_G() .
I would like to know if anybody has ever succeeded to delete a graph
generated in this way or to iterate over a SPARQL statement referencing to
a such a graph inside a stored procedure (the same SPARQL statement run
interactively works).
Who is interested in reproducing the problem below there is what I think
should allow it.
I use Virtuoso Open Source Edition (multi threaded)
Version 7.2.4.3217-threads as of Apr 25 2016
Compiled for Win64 (x86_64-generic-win-64)
Thanks!
Cheers
Beppe
*Deletion Problem*
I have executed the basic.sql example given by OpenLink Software about how
to use R2RML <http://docs.openlinksw.com/virtuoso/r2rmlhow/>and I see that
the generated RDF graph cannot be deleted. At the bottom of this e-mail
there is the session in which I run the example and the graph deletion
fails.
*Iteration over a SPARQL query*
After executing the basic.sql example the following commands allow to
perform an iteration on the graph.
create procedure R2RML.TEST.try() returns integer
{
for (sparql define input:storage ""
select ?o
#from <http://localhost:8890/sparql>
from <http://example.com/>
where { ?s ?p ?o } LIMIT 5 ) do
{
string_to_file ('trashMe.txt', "o"||'\n', -1);
};
};
R2RML.TEST.try();
In my installation no iteration is performed with these commands. Changing
with a non-generated graph instead (for example the commented out one) the
iterations are performed.
I have reinstalled Virtuoso Open Source for Windows together with the
rdb2rdf_dav vad package (from here)
<http://s3.amazonaws.com/opldownload/uda/vad-packages/7.0/rdb2rdf_dav.vad>before
performing the test, in order to have an environment unaffected by previous
operations.
SQL> load .\basic.sql;
Done. -- 4 msec.
Done. -- 16 msec.
Done. -- 0 msec.
Done. -- 0 msec.
Done. -- 0 msec.
STATE MESSAGE
VARCHAR VARCHAR
_______________________________________________________________________________
00000 IRI class <r2rml:virt02-d6310c8f81a31b40880be84617cef62c> has been
defined (inherited from rdfdf:sql-integer-uri-nullable)
00000 Literal class <r2rml:virt02-bf406ba67f39c90ee07c9e8b9f0611ae> has
been defined (inherited from rdfdf:sql-integer-literal-nullable)
00000 Quad storage <
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage> is flagged as
being edited
00000 Quad map <http://temp/product> has been created and added to the <
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage>
00000 Quad map <sys:qm-0b840fec4c625440d1915a0ae8e5cab9> has been
created and added to the <
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage>
00000 Quad map <sys:qm-84e7c00e26da8476895ddc0d779d2538> has been
created and added to the <
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage>
00000 Quad map <sys:qm-60348ca058fc088a9c89f6e10efc15f9> has been
created and added to the <
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage>
00000 Quad storage <
http://www.openlinksw.com/schemas/virtrdf#DefaultQuadStorage> is unflagged
and can be edited by other transactions
00000 Transaction committed, SPARQL compiler re-configured
00000 9 RDF metadata manipulation operations done
10 Rows. -- 297 msec.
SQL>
SQL>
SQL> sparql select * from <http://example.com/> where {?s ?p
?o};
s
p o
LONG VARCHAR LONG
VARCHAR LONG VARCHAR
___________________________________
http://example.com/product/1 http://example.com/product#id
1
http://example.com/product/1 http://example.com/product#name
Virtuoso
http://example.com/product/1
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://example.com/ns#product
3 Rows. -- 16
msec.
SQL>
SQL> SPARQL CLEAR GRAPH <http://example.com/>;
callret-0
LONG
VARCHAR
____________________________________________________________________
Clear graph <http://example.com/> --
done
1 Rows. -- 16
msec.
SQL>
SQL>
SQL> sparql select * from <http://example.com/> where {?s ?p
?o};
s
p o
LONG VARCHAR LONG
VARCHAR LONG VARCHAR
__________________________________
http://example.com/product/1 http://example.com/product#id
1
http://example.com/product/1 http://example.com/product#name
Virtuoso
http://example.com/product/1
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://example.com/ns#product
3 Rows. -- 15
msec.
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