[redland-dev] bug in rasqal

[Dave Beckett]

Pierre-Antoine Champin wrote:
> Hi,
> 
> It seems to me that rasqal 0.9.15 is bugged with regard to FILTER
> embeded in an OPTIONAL pattern
> 
> see http://www.w3.org/TR/rdf-sparql-query/#OptionalAndConstraints
> 
> the result with rasqal is
> 
> result: [title=string("The Semantic Web"),
> price=string("23"^^<http://www.w3.org/2001/XMLSchema#integer>)]
> roqet: Query returned 1 results
> 
> Seems that the FILTER is filtering at the "top level", not only the
> subresults of the optional pattern.
> 
> NB: I could not test rasqal 0.9.16 (sorry about that), but the release
> note does not mention any bugfix related to filter, so I assume it is
> still there...

OPTIONAL is buggy - there are several bugs reported on this:
http://bugs.librdf.org/mantis/view.php?id=77
http://bugs.librdf.org/mantis/view.php?id=119
http://bugs.librdf.org/mantis/view.php?id=261

This particular case is not working; optional & filter do
only work at the top level.

The fix is rewrite the query engine, which I'm doing, rather slowly
since it's in my spare time.

Dave