[jira] [Created] (JENA-705) Sequence of joins of sub-queries gives incorrect answer

["Rob Vesse (JIRA)" <ji...@apache.org>]

Rob Vesse created JENA-705:
------------------------------

             Summary: 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


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 (add {{--engine=ref}}), disable the optimiser (add {{--set arq:optimizer=false}}) or disable the index join strategy (add {{--set arq:optIndexJoinStrategy=false}}) 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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