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Posted to dev@hive.apache.org by "Namit Jain (JIRA)" <ji...@apache.org> on 2009/02/01 00:29:59 UTC
[jira] Commented: (HIVE-262) outer join gets some duplicate rows in
some scenarios
[ https://issues.apache.org/jira/browse/HIVE-262?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12669286#action_12669286 ]
Namit Jain commented on HIVE-262:
---------------------------------
Ashish suggested the following approach:
Based on join conditions, create a set of all tables being joined (no outer join), and if one of them is null for a given value, all of them become null.
For example,
A join B on A.c1=B.c1 join C on A.c1=C.c1 right outer join D on A.c1=D.c1
A,B,C belong to the same group (since A joins with B and A joins with C).
So, for a given key (c1), if there is no row corresponding to either of A, B, or C - assume that
there is no row for all of them for that key.
That works for the example above, and the approach is different from the patch
> outer join gets some duplicate rows in some scenarios
> -----------------------------------------------------
>
> Key: HIVE-262
> URL: https://issues.apache.org/jira/browse/HIVE-262
> Project: Hadoop Hive
> Issue Type: Bug
> Components: Query Processor
> Affects Versions: 0.2.0
> Reporter: Namit Jain
> Assignee: Namit Jain
> Priority: Blocker
> Fix For: 0.2.0
>
> Attachments: patch.262.1.txt, patch262.2.txt
>
>
> SELECT * FROM src src1 JOIN src src2 ON (src1.key = src2.key AND src1.key < 10) RIGHT OUTER JOIN src src3 ON (src1.key = src3.key AND src3.key < 20);
> returns duplicate rows for outer join
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