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https://issues.apache.org/jira/browse/CALCITE-3355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16984431#comment-16984431
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Chunwei Lei commented on CALCITE-3355:
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I open a pr for this(sorry for the delay~). [~kirillkozlov] , could you please
take a look?
> Deduce whether CASE and COALESCE may produce NULL values
> --------------------------------------------------------
>
> Key: CALCITE-3355
> URL: https://issues.apache.org/jira/browse/CALCITE-3355
> Project: Calcite
> Issue Type: Bug
> Components: core
> Affects Versions: 1.20.0
> Reporter: Kirill Kozlov
> Assignee: Chunwei Lei
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> When executing queries like:
> "SELECT COALESCE(name, 'unknown') as name_out FROM PCOLLECTION"
> (input 'name' is nullable)
> There is a need to know whether the result is nullable or not (in this case -
> not). During validation stage "COALESCE" is being transformed (via
> SqlValidatorImpl.performUnconditionalRewrites) into a "CASE" statement, which
> currently does not determine nullability of a result.
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