Hello Gregory, Yes I confirm that this is my fault. An optimizer tries to simplify the query a bit bu in the middle of the process it fails to prove that the transformation is valid step-by-step. It it were a bit more lazy and did not check every single step then it would provide a valid final result (at least in this particular case), but it stays on a safe side. I'll try to make the prover better, if failed then I'll disable the transformation for cases like this but the fix is coming soon in any case.
Best Regards, Ivan Mikhailov OpenLink Software http://virtuoso.openlinksw.com On Thu, 2010-09-30 at 16:14 -0400, Gregory Williams wrote: > I'm running into what seems like a bug in virtuoso's SPARQL optimizer. I'm > trying to execute a query using the OPTIONAL/!BOUND trick for negation and > getting this error message: > > Internal error: sparp_gp_detach_all_filters(): optimization tries to break > the semantics of LEFT OUTER JOIN for OPTIONAL clause > > MacTed on #swig told me to send along a copy of the EXPLAIN for the query to > the list, but EXPLAIN gives me the same error. Strangely, this seems to > happen only when the optional/filter are within a GRAPH graph pattern. The > query I'm trying to execute is: > > > PREFIX dcterms: <http://purl.org/dc/terms/> > PREFIX void: <http://rdfs.org/ns/void#> > SELECT DISTINCT ?dataset ?modified > WHERE { > GRAPH <http://kasei.us/temp/data-gov-times.rdf> { > ?dataset a void:Dataset; > dcterms:modified ?modified . > OPTIONAL { > ?dataset dcterms:modified ?m1 . > FILTER(?m1 > ?modified) > } > FILTER(!BOUND(?m1)) > } > } > ORDER BY ?dataset > > I'm using virtuoso 06.01.3127. Any thoughts on how to get around this problem > and when this might be fixed (perhaps it is in 6.2?) would be greatly > appreciated. > > thanks, > .greg > > > ------------------------------------------------------------------------------ > Start uncovering the many advantages of virtual appliances > and start using them to simplify application deployment and > accelerate your shift to cloud computing. > http://p.sf.net/sfu/novell-sfdev2dev > _______________________________________________ > Virtuoso-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/virtuoso-users
