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https://issues.apache.org/jira/browse/JENA-2288?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17497039#comment-17497039
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Andy Seaborne commented on JENA-2288:
-------------------------------------
[~LorenzB]'s analysis looks right.
I can't reproduce this using Fuseki as the SERVICE target, and looking at the
execution, I don't see a way for the grand total count to leak back to the
outer query as it is never calculated. May be it's the duplicates for the path
confuse the at the far end.
This ticket is "Cannot reproduce".
> Counting aggregation inside SERVICE provides wrong result
> ---------------------------------------------------------
>
> Key: JENA-2288
> URL: https://issues.apache.org/jira/browse/JENA-2288
> Project: Apache Jena
> Issue Type: Bug
> Affects Versions: Jena 4.4.0
> Reporter: Dmitry Zhelobanov
> Priority: Major
>
> Here is a query which retrieves museums in the specific city:
> {code:java}
> PREFIX wd: <http://www.wikidata.org/entity/>
> PREFIX wdt: <http://www.wikidata.org/prop/direct/>
> SELECT ?wikidata_iri ?museum
> WHERE {
> VALUES (?wikidata_iri) { (<http://www.wikidata.org/entity/Q612>) } .
>
> SERVICE <https://query.wikidata.org/sparql> {
> {
> select ?wikidata_iri ?museum
> where {
> OPTIONAL {
> ?museum (wdt:P131)+ ?wikidata_iri ;
> wdt:P31/(wdt:P279)* wd:Q33506 .
> }
> }
> }
> }
> } {code}
> This query returns 3 results:
> |<http://www.wikidata.org/entity/Q612>|<http://www.wikidata.org/entity/Q2125281>|
> |<http://www.wikidata.org/entity/Q612>|<http://www.wikidata.org/entity/Q28736367>|
> |<http://www.wikidata.org/entity/Q612>|<http://www.wikidata.org/entity/Q67737768>|
> And here is a query which is supposed to count the number of the same museums
> in the same city:
> {code:java}
> PREFIX wd: <http://www.wikidata.org/entity/>
> PREFIX wdt: <http://www.wikidata.org/prop/direct/>
> SELECT ?wikidata_iri ?museum_count_in_city
> WHERE {
> VALUES (?wikidata_iri) { (<http://www.wikidata.org/entity/Q612>) } .
>
> SERVICE <https://query.wikidata.org/sparql> {
> {
> select ?wikidata_iri (COUNT(?museum) as ?museum_count_in_city)
> where {
> OPTIONAL {
> ?museum (wdt:P131)+ ?wikidata_iri ;
> wdt:P31/(wdt:P279)* wd:Q33506 .
> }
> } group by ?wikidata_iri
> }
> }
> }{code}
> But the count value produced by the query is wrong:
> |<[http://www.wikidata.org/entity/Q612]>|"201"{^}^^<[http://www.w3.org/2001/XMLSchema#integer]>{^}|
> It outputs *201* instead of expected *3.*
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