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Posted to issues@calcite.apache.org by "ASF GitHub Bot (Jira)" <ji...@apache.org> on 2019/11/28 07:45:00 UTC

[jira] [Updated] (CALCITE-3355) Deduce whether CASE and COALESCE may produce NULL values

     [ https://issues.apache.org/jira/browse/CALCITE-3355?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

ASF GitHub Bot updated CALCITE-3355:
------------------------------------
    Labels: pull-request-available  (was: )

> 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
>
> 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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