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  1. Calcite
  2. CALCITE-3198

Enhance RexSimplify to handle (x<>a or x<>b)

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    Details

    • Type: Improvement
    • Status: Closed
    • Priority: Minor
    • Resolution: Fixed
    • Affects Version/s: 1.20.0
    • Fix Version/s: 1.21.0
    • Component/s: None

      Description

      Currently, ReduceExpressionsRule.FILTER_INSTANCE can successfully reduce a query like this one (see RelOptRulesTest#testReduceConstantsDup):

      // query:
      select d.deptno from dept d where d.deptno=7 and d.deptno=8
      
      // plan before:
      LogicalProject(DEPTNO=[$0])
        LogicalFilter(condition=[AND(=($0, 7), =($0, 8))])
          LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
      
      // plan after:
      LogicalProject(DEPTNO=[$0])
        LogicalValues(tuples=[[]])
      

      As we can see, since the filter is 'always false', the LogicalTableScan+LogicalFilter are correctly replaced by an empty LogicalValues.

      However, the same filter with a NOT expression, is not correctly simplified:

      // query:
      select d.deptno from dept d where not(d.deptno=7 and d.deptno=8)
      
      // plan before:
      LogicalProject(DEPTNO=[$0])
        LogicalFilter(condition=[NOT(AND(=($0, 7), =($0, 8)))])
          LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
      
      // plan after (actual, NOT distributivity for AND):
      LogicalProject(DEPTNO=[$0])
        LogicalFilter(condition=[OR(<>($0, 7), <>($0, 8))])
          LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
      
      // plan after (expected, when $0's type is NOT nullable, filter removed):
      LogicalProject(DEPTNO=[$0])
        LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
      
      // plan after (expected, when $0's type IS nullable, filter simplified as IS NOT NULL):
      LogicalProject(DEPTNO=[$0])
        LogicalFilter(condition=[IS NOT NULL($0)])
          LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
      

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              • Assignee:
                rubenql Ruben Q L
                Reporter:
                rubenql Ruben Q L
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                  Updated:
                  Resolved:

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