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https://issues.apache.org/jira/browse/CALCITE-545?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14253749#comment-14253749
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Julian Hyde commented on CALCITE-545:
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[~ashutoshc] This is the issue we discussed the other day. Anything I missed?
> When a projected expression can only have one value, replace with that
> constant
> -------------------------------------------------------------------------------
>
> Key: CALCITE-545
> URL: https://issues.apache.org/jira/browse/CALCITE-545
> Project: Calcite
> Issue Type: Bug
> Reporter: Julian Hyde
> Assignee: Julian Hyde
>
> When we have deduced that an expression can only have one value, replace the
> expression with that value. This is beneficial because it will allow us to do
> more column trimming.
> Example 1
> {{select deptno from emp where deptno = 10}}
> can become
> {{select 10 from emp where deptno = 10}}
> Example 2 (using inference, as in CALCITE-360)
> {{select emp.deptno
> from emp join dept using (deptno)
> where dept.deptno = 10}}
> can become
> {{select 10
> from emp join dept using (deptno)
> where dept.deptno = 10}}
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