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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 edited comment on JENA-2288 at 2/24/22, 1:45 PM:
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[~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. Maybe it's the duplicates for the path
confusing the far end.
This ticket is "Cannot reproduce". Please reopen if you have an example that
does not depend on the characteristics of another system.
was (Author: andy.seaborne):
[~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. Maybe it's the duplicates for the path
confusing the far end.
This ticket is "Cannot reproduce". Please reopen if you have a example that
does not depend on the characteristics of another system.
> 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
> Assignee: Andy Seaborne
> 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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