> 4/ You can use a subselect to restrict the remote query part:
>
>
> SERVICE <...> {
> SELECT * {
> ...
> } LIMIT 300
> }
I tried this query:
SELECT DISTINCT ?comment WHERE {
SERVICE
<http://api.talis.com/stores/bbc-backstage/services/sparql>
{ ?thCenturyClassicalComposers0
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://dbpedia.org/class/yago/20thCenturyClassicalComposers>
}
SERVICE <http://dbpedia.org/sparql> {SELECT
?thCenturyClassicalComposers0 ?comment WHERE {
?thCenturyClassicalComposers0
<http://www.w3.org/2000/01/rdf-schema#comment> ?comment } }
}
It returns results in a very correct time.
Then I remove ?thCenturyClassicalComposers0 from the sub-SELECT:
SELECT DISTINCT ?comment WHERE {
SERVICE
<http://api.talis.com/stores/bbc-backstage/services/sparql>
{ ?thCenturyClassicalComposers0
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<http://dbpedia.org/class/yago/20thCenturyClassicalComposers>
}
SERVICE <http://dbpedia.org/sparql> {SELECT ?comment WHERE {
?thCenturyClassicalComposers0
<http://www.w3.org/2000/01/rdf-schema#comment> ?comment } }
}
This query now takes MUCH MUCH longer. And eventually fizzles in a 509
HttpException.
Any idea why the query plan goes so wrong when
?thCenturyClassicalComposers0 is absent of the sub-SELECT.
?
