- From: Reto Gmür <reto@factsmission.com>
- Date: Thu, 13 Sep 2018 12:42:32 +0000
- To: "public-sparql-dev@w3.org" <public-sparql-dev@w3.org>
Hi,
With 5 Triples stores I'm getting 3 different results for the following query:
select ?x ?y where {
values ?x { 1 2 }
OPTIONAL {
select ?y where {
{
values ?y { 5 6 }
} UNION {
bind (?x as ?y)
}
}
}
}
According to the spec subqueries are evaluated logically first [1], however I noticed implementations behaving differently and a conversation [2] on this list in June 2016 questioning this requirement.
>From RDF4J persistent store (in a FluidOps information workbench) I get the following answer:
+---+---+
| x | y |
+---+---+
| 1 | 5 |
| 1 | 6 |
| 1 | 1 |
| 2 | 5 |
| 2 | 6 |
| 2 | 2 |
+---+---+
>From Fuseki, GraphDB and StarDog I get the following answer:
+---+---+
| x | y |
+---+---+
| 1 | 5 |
| 1 | 6 |
| 1 | |
| 2 | 5 |
| 2 | 6 |
| 2 | |
+---+---+
>From virtuoso store (htttp://dbpedia.org/sparql) I get the following answer:
| x | y |
+---+---+
| 1 | |
| 2 | |
+---+---+
I assume that the majority is right with the second result. Is this assumption correct?
Cheers,
Reto
1. https://www.w3.org/TR/sparql11-query/#subqueries
2. https://lists.w3.org/Archives/Public/public-sparql-dev/2016AprJun/0026.html
Received on Thursday, 13 September 2018 12:42:57 UTC