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Posted to dev@jena.apache.org by "Andy Seaborne (JIRA)" <ji...@apache.org> on 2014/05/29 15:45:02 UTC
[jira] [Commented] (JENA-705) Sequence of joins of sub-queries
gives incorrect answer
[ https://issues.apache.org/jira/browse/JENA-705?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14012360#comment-14012360 ]
Andy Seaborne commented on JENA-705:
------------------------------------
I get the same algebra for 2.11.0 and 2.11.1 (and 2.10.1, not 2.10.1).
So I don't think its the JoinClassifier itself, but it is to do with execution of the structure it creates. I have a lesser query (query-subset.rq) but it does seem to need to have 3 of the 4 inner SELECTs to illustrate the problem. It has no UNIONs.
> Sequence of joins of sub-queries gives incorrect answer
> -------------------------------------------------------
>
> Key: JENA-705
> URL: https://issues.apache.org/jira/browse/JENA-705
> Project: Apache Jena
> Issue Type: Bug
> Components: ARQ
> Affects Versions: Jena 2.11.1
> Reporter: Rob Vesse
> Assignee: Andy Seaborne
> Priority: Critical
> Attachments: data-subset.ttl, data.ttl, query.rq
>
>
> This issue comes out of a stack overflow question at http://stackoverflow.com/questions/23899841/jenas-subquery-intersection-returns-empty-contrary-to-the-results-from-protege?noredirect=1#comment36813625_23899841 about differences between query results in Protege and Jena
> From both the SO question and my own experimentation this does indeed appear to be a bug.
> I'll attach the query and dataset afterwards but essentially the following behaviour can be observed.
> With 2.11.0 the following returns results:
> {noformat}
> > ./sparql --query query.rq --data data.ttl
> ---------------------------------------------------------------------------------------------------------------------------------------
> | offering |
> =======================================================================================================================================
> | <http://PricingAPIAmazonOnDemandOfferings.com#hs1.8xlarge_3440_TIME247806284122937linux-AmazonOnDemandInstance_TIME247806284128497> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#m1.xlarge_3044_TIME247806261045248linux-AmazonOnDemandInstance_TIME247806261052518> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#cr1.8xlarge_3330_TIME247806279000311linux-AmazonOnDemandInstance_TIME247806279016134> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#m1.medium_3000_TIME247806258807012linux-AmazonOnDemandInstance_TIME247806258833953> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#m2.xlarge_3264_TIME247806274243312linux-AmazonOnDemandInstance_TIME247806274255286> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#c3.8xlarge_3154_TIME247806266383402linux-AmazonOnDemandInstance_TIME247806266391099> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#m1.large_3022_TIME247806259925275linux-AmazonOnDemandInstance_TIME247806259933827> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#c1.xlarge_3198_TIME247806269972105linux-AmazonOnDemandInstance_TIME247806269986217> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#i2.2xlarge_3374_TIME247806281161573linux-AmazonOnDemandInstance_TIME247806281167987> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#cc2.8xlarge_3220_TIME247806271984550linux-AmazonOnDemandInstance_TIME247806271997379> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#hi1.4xlarge_3462_TIME247806285100936linux-AmazonOnDemandInstance_TIME247806285106495> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#i2.xlarge_3352_TIME247806280140383linux-AmazonOnDemandInstance_TIME247806280147225> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#c3.4xlarge_3132_TIME247806265310896linux-AmazonOnDemandInstance_TIME247806265318593> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#m2.2xlarge_3286_TIME247806275687432linux-AmazonOnDemandInstance_TIME247806275695557> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#m2.4xlarge_3308_TIME247806277291059linux-AmazonOnDemandInstance_TIME247806277311157> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#c3.2xlarge_3110_TIME247806264234541linux-AmazonOnDemandInstance_TIME247806264242239> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#i2.4xlarge_3396_TIME247806282156677linux-AmazonOnDemandInstance_TIME247806282162664> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#i2.8xlarge_3418_TIME247806283147932linux-AmazonOnDemandInstance_TIME247806283153491> |
> | <http://PricingAPIAmazonOnDemandOfferings.com#m3.2xlarge_2956_TIME247806256606408linux-AmazonOnDemandInstance_TIME247806256614533> |
> ---------------------------------------------------------------------------------------------------------------------------------------
> {noformat}
> However with 2.11.1 or with current trunk it returns no results:
> {noformat}
> > ./sparql --query query.rq --data data.ttl
> ------------
> | offering |
> ============
> ------------
> {noformat}
> However if we use the reference engine i.e.
> {noformat}
> > ./sparql --query query.rq --data data.ttl --engine=ref
> {noformat}
> Or disable the optimiser i.e.
> {noformat}
> > ./sparql --query query.rq --data data.ttl --set arq:optimization=false
> {noformat}
> Or disable the index join strategy i.e.
> {noformat}
> > ./sparql --query query.rq --data data.ttl --set arq:optIndexJoinStrategy=false
> {noformat}
> Then we do get the same results as 2.11.0 returned
> Therefore this looks to be a change in behaviour in index join strategy introduced in 2.11.1
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