Thank you for the link Lorenz. Yes it behaves the same with the same data,
in my test it had a different dataset where ?xLabel was bound but with no
matching ?x variable.
Someone has recently elaborated on this with regards to Jena here.
https://newbedev.com/sparql-optional-query
On Thu, Aug 5,
That shouldn't happen for Blazegraph, especially as they even have a
blog entry for this topic, dubbed "order matters":
https://github.com/blazegraph/database/wiki/SPARQL_Order_Matters
You can check the Blazegraph query plan as well, just put
=details to the request URL
You can also try to
OK yes, thank you for the algebra hint and implicit empty graph pattern
Andy. Blazegraph has thrown me off here since it seems to interpret the
query differently. without preserving the table unit on the left hand side
I presume.
On Tue, Aug 3, 2021 at 6:20 PM Andy Seaborne wrote:
>
>
> On
On 03/08/2021 17:38, Marco Neumann wrote:
I have just noticed that the following query pattern with optionals yields
undesirable SPARQL query results if the variable (?xLabel) isn't bound.
Let the data be: :x :p :y
SELECT ?x
WHERE{
OPTIONAL{ ?x rdfs:label ?xLabel.}
?x :p ?y.
}
(join
