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https://issues.apache.org/jira/browse/PIG-927?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12768027#action_12768027
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Daniel Dai commented on PIG-927:
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Hi, Alan,
Thank you for your comment. For the test case, if we do not have this patch,
"1\t" for input1 will merge with "1\t" for input2, thus "join" will produce 2
output records. With this patch, we can only see 1 output record.
> null should be handled consistently in Join
> -------------------------------------------
>
> Key: PIG-927
> URL: https://issues.apache.org/jira/browse/PIG-927
> Project: Pig
> Issue Type: Bug
> Affects Versions: 0.4.0
> Reporter: Pradeep Kamath
> Assignee: Daniel Dai
> Fix For: 0.6.0
>
> Attachments: PIG-927-1.patch, PIG-927-2.patch
>
>
> Currenlty Pig mostly follows SQL semantics for handling null. However there
> are certain cases where pig may need to handle nulls correctly. One example
> is the join - joins on single keys results in null keys not matching to
> produce an output. However if the join is on >1 keys, in the key tuple, if
> one of the values is null, it still matches with another key tuple which has
> a null for that value. We need to decide the right semantics here.
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