[jira] [Work started] (HIVE-14431) Recognize COALESCE as CASE and extend CASE simplification to cover more cases

["Jesus Camacho Rodriguez (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-14431?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on HIVE-14431 started by Jesus Camacho Rodriguez.
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> Recognize COALESCE as CASE and extend CASE simplification to cover more cases
> -----------------------------------------------------------------------------
>
>                 Key: HIVE-14431
>                 URL: https://issues.apache.org/jira/browse/HIVE-14431
>             Project: Hive
>          Issue Type: Improvement
>          Components: CBO
>    Affects Versions: 2.2.0
>            Reporter: Jesus Camacho Rodriguez
>            Assignee: Jesus Camacho Rodriguez
>
> Transform:
> {code}
> (COALESCE(a, '')  = '') OR
>            (a = 'A' AND b = c)  OR
>            (a = 'B' AND b = d) OR
>            (a = 'C' AND b = e) OR
>            (a = 'D' AND b = f) OR
>            (a = 'E' AND b = g) OR
>            (a = 'F' AND b = h)
> {code}
> into:
> {code}
> (a='') OR
>            (a is null) OR
>            (a = 'A' AND b = c)  OR
>            (a = 'B' AND b = d) OR
>            (a = 'C' AND b = e) OR
>            (a = 'D' AND b = f) OR
>            (a = 'E' AND b = g) OR
>            (a = 'F' AND b = h)
> {code}
> With complex queries, this will lead us to factor more predicates that could be pushed to the TS.



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