[jira] [Commented] (CALCITE-895) ReduceExpressionsRule.FILTER_INSTANCE does not simplify a Filter, which has “Case-When IsNull” under OR/AND

["Sean Hsuan-Yi Chu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-895?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14901560#comment-14901560 ] 

Sean Hsuan-Yi Chu commented on CALCITE-895:
-------------------------------------------

Pull request: https://github.com/apache/incubator-calcite/pull/135
[~julianhyde] Can you help review? 

> ReduceExpressionsRule.FILTER_INSTANCE does not simplify a Filter, which has “Case-When IsNull” under OR/AND
> -----------------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-895
>                 URL: https://issues.apache.org/jira/browse/CALCITE-895
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>            Reporter: Sean Hsuan-Yi Chu
>            Assignee: Sean Hsuan-Yi Chu
>
> For example, a query like this:
> {code}
> select *
> from emp
> where case when sal = 1000 then null else 1 end is null OR sal = 2000
> {code}
> The condition in the filter can be rewritten as "sal = 1000 OR sal = 2000". However, for now, Calcite does not do the simplification. Instead, Calcite output this plan:
> {code}
> LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
>   LogicalFilter(condition=[OR(IS NULL(CASE(=($5, 1000), null, 1)), =($5, 2000))])
>     LogicalTableScan(table=[[CATALOG, SALES, EMP]])
> {code}



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