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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-5304) Queries fail intermittently when there is skew in data distribution
Date Thu, 02 Mar 2017 21:00:48 GMT

    [ https://issues.apache.org/jira/browse/DRILL-5304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15892996#comment-15892996
] 

ASF GitHub Bot commented on DRILL-5304:
---------------------------------------

Github user asfgit closed the pull request at:

    https://github.com/apache/drill/pull/766


> Queries fail intermittently when there is skew in data distribution
> -------------------------------------------------------------------
>
>                 Key: DRILL-5304
>                 URL: https://issues.apache.org/jira/browse/DRILL-5304
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>    Affects Versions: 1.10.0
>            Reporter: Abhishek Girish
>            Assignee: Padma Penumarthy
>              Labels: ready-to-commit
>         Attachments: query1_drillbit.log.txt, query2_drillbit.log.txt
>
>
> In a distributed environment, we've observed certain queries to fail execution intermittently,
with an assignment logic issue, when the underlying data is skewed w.r.t distribution. 
> For example the TPC-H [query 7|https://github.com/mapr/drill-test-framework/blob/master/framework/resources/Advanced/tpch/tpch_sf100/parquet/07.q]
failed with the below error:
> {code}
> java.sql.SQLException: SYSTEM ERROR: IllegalArgumentException: MinorFragmentId 105 has
no read entries assigned
> ...
>   (org.apache.drill.exec.work.foreman.ForemanException) Unexpected exception during fragment
initialization: MinorFragmentId 105 has no read entries assigned
>     org.apache.drill.exec.work.foreman.Foreman.run():281
>     java.util.concurrent.ThreadPoolExecutor.runWorker():1145
>     java.util.concurrent.ThreadPoolExecutor$Worker.run():615
>     java.lang.Thread.run():744
>   Caused By (java.lang.IllegalArgumentException) MinorFragmentId 105 has no read entries
assigned
> {code}
> Log containing full stack trace is attached.
> And for this query, the underlying TPC-H SF100 Parquet dataset was observed to be located
mostly only on 2-3 nodes on an 8 node DFS environment. The data distribution skew on this
cluster is most likely the triggering factor for this case, as the same query, on the same
dataset does not show this failure on a different test cluster (with possibly different data
distribution). 
> Also, another [query|https://github.com/mapr/drill-test-framework/blob/master/framework/resources/Functional/limit0/window_functions/bugs/data/drill-3700.sql]
failed with a similar error when slice target was set to 1. 
> {code}
> Failed with exception
> java.sql.SQLException: SYSTEM ERROR: IllegalArgumentException: MinorFragmentId 66 has
no read entries assigned
> ...
>   (org.apache.drill.exec.work.foreman.ForemanException) Unexpected exception during fragment
initialization: MinorFragmentId 66 has no read entries assigned
> {code}



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