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https://issues.apache.org/jira/browse/CALCITE-1116?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15198090#comment-15198090
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Julian Hyde commented on CALCITE-1116:
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I renamed "filterCondition" to "unknownAsFalse" to make the semantics explicit.
I still have doubts about how we approach null semantics. I think it's very
difficult to catch every last bug. For example, it doesn't seem valid to pass
unknownAsFalse unchanged into simplifyNot. If you have {{WHERE NOT (a < 10 AND
a >= 10)}}, {{WHERE}} will treat an unknown result of {{NOT (a < 10 AND a >=
10)}} as false, but that would mean treating an unknown result of {{a < 10 AND
a >= 10}} as true. I think there are similar issues in CASE. I don't propose
that you or we fix all of these problems; we should just spray-paint
"architecturally unsafe" on the whole thing and start looking for a better
solution.
With these reservations, patch looks good, and I will commit shortly.
> Extend simplify for reducing expressions
> ----------------------------------------
>
> Key: CALCITE-1116
> URL: https://issues.apache.org/jira/browse/CALCITE-1116
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Fix For: 1.7.0
>
>
> We would like to cover more cases in expression simplification, such as:
> x>5 and x is not null => x>5
> x>5 and x is null => not satisfiable
> x>5 and x<=5 => not satisfiable
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