[jira] [Commented] (CALCITE-1413) New CASE statement simplification

["Julian Hyde (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-1413?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15549180#comment-15549180 ] 

Julian Hyde commented on CALCITE-1413:
--------------------------------------

Makes sense. This generalizes work done in CALCITE-1220, where e1 and e2 had to be constants (TRUE or FALSE).

It's worth pulling in CALCITE-1054, which uses RexNode rewrites to convert 3-valued booleans to 2-valued booleans.

> New CASE statement simplification
> ---------------------------------
>
>                 Key: CALCITE-1413
>                 URL: https://issues.apache.org/jira/browse/CALCITE-1413
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.9.0
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>             Fix For: 1.11.0
>
>
> Another possible simplification for CASE statements that return boolean values.
> {code:sql}
> CASE
>  WHEN p1 THEN e1
>  WHEN p2 THEN e2
>  ELSE TRUE
> END
> {code}
> where e1...en are boolean expressions, can be rewritten into:
> {code:sql}
> (p1 and e1) or (p2 and e2 and not(p1)) or (not(p1) and not(p2))
> {code}
> if p1...pn cannot be nullable.



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