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From "Jinfeng Ni (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DRILL-1335) Merge Join incorrectly return unqualified rows when join key is null.
Date Tue, 26 Aug 2014 19:17:58 GMT

     [ https://issues.apache.org/jira/browse/DRILL-1335?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jinfeng Ni updated DRILL-1335:
------------------------------

    Attachment: 0001-DRILL-1335-Fix-merge-join-operator-when-compare-null.patch

> Merge Join incorrectly return unqualified rows when join key is null. 
> ----------------------------------------------------------------------
>
>                 Key: DRILL-1335
>                 URL: https://issues.apache.org/jira/browse/DRILL-1335
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Jinfeng Ni
>            Assignee: DrillCommitter
>         Attachments: 0001-DRILL-1335-Fix-merge-join-operator-when-compare-null.patch
>
>
> Drill's merge join operator incorrectly returns unqualified rows, when join key is null
value.  For example,
> alter session set `planner.enable_hashjoin` = false;
> // Q1
> select * from cp.`region.json` t1, cp.`region.json` t2 where t1.non_exist = t2.non_exist2
;
> Q1 should return 0 rows, since both left and right side of join comparison are NULL values.
But Drill will return 12100 rows. 
> The cause of this problem is MergeJoin operator thinks a comparison between NULL and
NULL is a qualified condition, and returns that pair of joining row.



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