Problems related to initialBindings about comunica

[github-actions]

Thanks for reporting!

[rubensworks]

Thanks for reporting these findings @bergos!

@joachimvh I suspect this is similar to recent issues you fixed in the algebra (#1223 and #1294). Could you check if this is something that needs changes in the algebra? If not, I can have a closer look to see if changes are needed on the Comunica-side.

[joachimvh]

@joachimvh I suspect this is similar to recent issues you fixed in the algebra (#1223 and #1294). Could you check if this is something that needs changes in the algebra?

Note that for both those issues I didn't take the initial bindings into account. There already was an issue with the original query without adding bindings when converting to algebra and back to SPARQL. So I had a look here to see if there also was a similar issue.

In this case the generated SPARQL query was the same as the original query (again without applying bindings), except for the one in pre-binding-002. There the output query is

SELECT ?this WHERE {
  FILTER("false"^^<http://www.w3.org/2001/XMLSchema#boolean> 
         && (?this = <http://datashapes.org/sh/tests/sparql/pre-binding/pre-binding-002.test#InvalidResource>))
}

So probably for that one there is a bug in the algebra where the filter scope gets pulled out of their group graph patterns and applied to a higher level. Tbh, reading the spec on this again, this is probably a misinterpretation I made when originally implementing this. I opened joachimvh/SPARQLAlgebra.js#105 for this.

But so for all the other ones I wouldn't know what the cause is. I didn't look into the effect of applying the bindings as I'm not sure how this works in Comunica. Is the query itself changed or is this applied afterwards?

[rubensworks]

So probably for that one there is a bug in the algebra where the filter scope gets pulled out of their group graph patterns and applied to a higher level. Tbh, reading the spec on this again, this is probably a misinterpretation I made when originally implementing this. I opened joachimvh/SPARQLAlgebra.js#105 for this.

Thanks! :-)

But so for all the other ones I wouldn't know what the cause is. I didn't look into the effect of applying the bindings as I'm not sure how this works in Comunica. Is the query itself changed or is this applied afterwards?

The handling of the initial bindings is done here, so mostly non-sparqlalgebrajs code indeed.