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https://issues.apache.org/jira/browse/CALCITE-7044?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17954923#comment-17954923
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xiong duan commented on CALCITE-7044:
-------------------------------------
I try to find the issue about 'case x when null then 1 else x + 2 end' but i
don't find it.
I think it's not available at the moment. If following this logic, CALCITE-7046
should have thrown an exception, but it returned NULL. Even though the result
is currently incorrect, this can verify that this logic does not exist.
> Add internal operator NOT NULL to enhance rewrite COALESCE operator
> -------------------------------------------------------------------
>
> Key: CALCITE-7044
> URL: https://issues.apache.org/jira/browse/CALCITE-7044
> Project: Calcite
> Issue Type: Bug
> Reporter: xiong duan
> Priority: Major
> Labels: pull-request-available
>
> Add internal operator NOT NULL to enhance rewrite COALESCE operator.
> This issue originated from the discussion of CALCITE-6978.
> A new NOT NULL internal operator was added, indicating that this expression
> will never be NULL.
> The expression coalesce(a,b) can be transformed into CASE WHEN a is not null
> THEN NOT NULL(a) ELSE b
> 1) `not null` operator doesn't do anything, just tell the validator this
> filed is not null.
> 2) When we do RelToSQL, we can ignore it directly.
> Notice:If the query contains nondeterministic function calls, like RANDOM.
> Duplicating such will produce different results,
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