[jira] [Commented] (HIVE-9015) Constant Folding optimizer doesn't handle expressions involving null

["Ashutosh Chauhan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-9015?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14233725#comment-14233725 ] 

Ashutosh Chauhan commented on HIVE-9015:
----------------------------------------

{code}
hive> explain select (null +4) from t1;
        TableScan
          Select Operator
            expressions: (null + 4) (type: double)
hive> explain select cast(null as double) from t1;
        TableScan
          Select Operator
            expressions: UDFToDouble(null) (type: double)
{code}
In both of these examples, expression can be folded to null at compile time, but it isn't.

> Constant Folding optimizer doesn't handle expressions involving null
> --------------------------------------------------------------------
>
>                 Key: HIVE-9015
>                 URL: https://issues.apache.org/jira/browse/HIVE-9015
>             Project: Hive
>          Issue Type: Task
>            Reporter: Ashutosh Chauhan
>
> Expressions which are guaranteed to evaluate to {{null}} aren't folded by optimizer yet.



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