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https://issues.apache.org/jira/browse/CALCITE-3049?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Julian Hyde updated CALCITE-3049:
---------------------------------
    Description: 
When simplifying expressions, revisit "IS NULL" if its argument has been 
simplified. For example, we currently simplify {code}(CASE WHEN FALSE THEN 
+(v0) ELSE -1 END) IS UNKNOWN{code} to {code}-1 IS UNKNOWN{code} but we should 
further simplify that to {{FALSE}}.

I have a preliminary [dev 
branch|https://github.com/julianhyde/calcite/tree/3049-simplify-is-null], but 
it needs a little more debugging. I'd be grateful if someone could finish it.

  was:
When simplifying expressions, revisit "IS NULL" if its argument has been 
simplified. For example, we currently simplify {code}(CASE WHEN FALSE THEN 
+(v0) ELSE -1 END) IS UNKNOWN{code} to {code}-1 IS UNKNOWN{code} but we should 
further simplify that to {{FALSE}}.

I have a preliminary dev branch, but it needs a little more debugging. I'd be 
grateful if someone could finish it.


> When simplifying expressions, revisit "IS NULL" if its argument has been 
> simplified
> -----------------------------------------------------------------------------------
>
>                 Key: CALCITE-3049
>                 URL: https://issues.apache.org/jira/browse/CALCITE-3049
>             Project: Calcite
>          Issue Type: Bug
>            Reporter: Julian Hyde
>            Priority: Major
>
> When simplifying expressions, revisit "IS NULL" if its argument has been 
> simplified. For example, we currently simplify {code}(CASE WHEN FALSE THEN 
> +(v0) ELSE -1 END) IS UNKNOWN{code} to {code}-1 IS UNKNOWN{code} but we 
> should further simplify that to {{FALSE}}.
> I have a preliminary [dev 
> branch|https://github.com/julianhyde/calcite/tree/3049-simplify-is-null], but 
> it needs a little more debugging. I'd be grateful if someone could finish it.



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