[jira] [Created] (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>]

Sean Hsuan-Yi Chu created CALCITE-895:
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             Summary: 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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