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https://issues.apache.org/jira/browse/PIG-1922?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13009384#comment-13009384
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Santhosh Srinivasan commented on PIG-1922:
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A cursory research on SQL and NULL reveals the following:
Reference: http://en.wikipedia.org/wiki/Null_(SQL)
1. For group by NULLs are considered equal (SQL 2003)
2. For joins NULLs are not equal
3. Use of (in)equality operator with NULL results in UNKNOWN (which is not the
same as NULL)
4. Only use of IS NULL and IS NOT NULL is defined as boolean
Based on the aforementioned points use of = and != should not error out but
should result in UNKNOWN. This looks like a slightly broader discussion.
Thoughts?
> null is being treated as string constant in expressions
> -------------------------------------------------------
>
> Key: PIG-1922
> URL: https://issues.apache.org/jira/browse/PIG-1922
> Project: Pig
> Issue Type: Bug
> Affects Versions: 0.8.0, 0.9.0
> Reporter: Thejas M Nair
> Fix For: 0.9.0
>
>
> In following statement, the null gets translated to string constant. The
> statement is invalid, and should result in an error.
> {code}
> fil = filter l by a != null; -- This does not give an error, the correct
> usage is "a is not null"
> fil = filter l by a != adsf; -- this does give an error message saying that
> there is no column asdf
> {code}
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