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https://issues.apache.org/jira/browse/PHOENIX-5065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16713423#comment-16713423
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James Taylor commented on PHOENIX-5065:
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Oracle treats the empty string the same as null, so there is a precedence. The
above queries look correct to me. Null is different than a value so WHERE
tenant_id = '' is the same as WHERE tenant_id = null which will never return
anything. If you want to find null values, you have to use WHERE tenant_id IS
NULL. The IN is like an OR, so same thing.
You can read more about the somewhat strange NULL trinary logic here:
https://en.wikipedia.org/wiki/Three-valued_logic
> Inconsistent treatment of NULL and empty string
> -----------------------------------------------
>
> Key: PHOENIX-5065
> URL: https://issues.apache.org/jira/browse/PHOENIX-5065
> Project: Phoenix
> Issue Type: Bug
> Affects Versions: 4.14.1
> Reporter: Geoffrey Jacoby
> Priority: Major
>
> Phoenix doesn't handle NULLs consistently with other SQL dialects, and it
> doesn't handle them consistently internally either.
> In PHOENIX-2422, [~jamestaylor] mentioned that Phoenix's intended behavior is
> for empty string and NULL to be equivalent. That's inconsistent with other
> SQL dialects (in which NULL is never equal to anything, including itself),
> but if that's our documented behavior, then that's fine unless PHOENIX-2422
> to change it is ever worked.
> But consider the following queries:
> {code:java}
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID = '';
> -- Returns 0 rows
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID IS NULL;
> -- Returns some number of rows. Call it N
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID IN ('');
> -- Returns 0 rows
> SELECT COUNT(*) FROM SYSTEM.CATALOG WHERE TENANT_ID IN ('', 'FOO');
> -- Returns N rows.
> {code}
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