[jira] [Comment Edited] (JENA-885) Poor performance and timeout failure with BIND in nested OPTIONALs

["Andy Seaborne (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/JENA-885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15090549#comment-15090549 ] 

Andy Seaborne edited comment on JENA-885 at 1/9/16 10:56 AM:
-------------------------------------------------------------

JENA-1023 should improve the execution performance of {{(leftjoin)}}.


was (Author: andy.seaborne):
This should improve the execution performance of {{(leftjoin)}}.

> Poor performance and timeout failure with BIND in nested OPTIONALs
> ------------------------------------------------------------------
>
>                 Key: JENA-885
>                 URL: https://issues.apache.org/jira/browse/JENA-885
>             Project: Apache Jena
>          Issue Type: Bug
>    Affects Versions: Jena 2.11.2
>            Reporter: Mark Buquor
>         Attachments: ExecuteTestQueries.java, GenerateTestDataset.java
>
>
> There appears to be a performance issue with BIND when used inside nested OPTIONALs. Affected queries fail to time out.
> The following patterns appear to be affected:
> {noformat}
> OPTIONAL { ... OPTIONAL { ... BIND ( ... ) } }
> OPTIONAL { ... OPTIONAL { ... } BIND ( ... ) }
> {noformat}
> The following patterns appear to be unaffected:
> {noformat}
> OPTIONAL { ... OPTIONAL { ... } } BIND ( ... )
> OPTIONAL { ...  BIND ( ... ) }
> OPTIONAL { ... } BIND ( ... )
> {noformat}
> So far, users have been able to work around the performance issue by rewriting their queries. However, the timeout failure is still a significant reliability issue, since affected queries consume resources and can run indefinitely. I've attached a testcase that exhibits the performance and timeout problems. Reproduced with a recent 2.13.0-SNAPSHOT build.
> {noformat}
> Execution Timeout (ms): 30000
> Query: PREFIX ex: <http://example.com/> SELECT ?s ?valueA { OPTIONAL { ?s ex:propA ?a . OPTIONAL { ?a ex:label ?labelA . } } BIND ( IF ( BOUND (?labelA), ?labelA, ?a) as ?valueA) }
> Execution time (ms): 586
> Execution time (ms): 143
> Query: PREFIX ex: <http://example.com/> SELECT ?s ?valueA { OPTIONAL { ?s ex:propA ?a . OPTIONAL { ?a ex:label ?labelA . } BIND ( IF ( BOUND (?labelA), ?labelA, ?a) as ?valueA) } }
> Execution time (ms): 110922
> Execution time (ms): 41004
> {noformat}



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