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Posted to issues@calcite.apache.org by "Chunwei Lei (Jira)" <ji...@apache.org> on 2019/09/19 02:47:00 UTC
[jira] [Comment Edited] (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:comment-tabpanel&focusedCommentId=16933010#comment-16933010 ]
Chunwei Lei edited comment on CALCITE-3355 at 9/19/19 2:46 AM:
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[~kirillkozlov] , I would like to take this issue if you don't mind.
was (Author: chunwei lei):
[~kirillkozlov] , I would like to task this issue if you don't mind.
> 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
> Priority: Major
>
> 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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