[jira] [Comment Edited] (CALCITE-3198) Enhance RexSimplify to handle (x<>a or x<>b)

["Ruben Quesada Lopez (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-3198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16903332#comment-16903332 ] 

Ruben Quesada Lopez edited comment on CALCITE-3198 at 8/8/19 9:16 PM:
----------------------------------------------------------------------

Ooops, my bad. Fixing it via https://github.com/apache/calcite/pull/1365


was (Author: rubenql):
Ooops, my bad. Fixing it...

> Enhance RexSimplify to handle (x<>a or x<>b)
> --------------------------------------------
>
>                 Key: CALCITE-3198
>                 URL: https://issues.apache.org/jira/browse/CALCITE-3198
>             Project: Calcite
>          Issue Type: Improvement
>    Affects Versions: 1.20.0
>            Reporter: Ruben Quesada Lopez
>            Assignee: Ruben Quesada Lopez
>            Priority: Minor
>              Labels: pull-request-available
>             Fix For: 1.21.0
>
>          Time Spent: 7h 40m
>  Remaining Estimate: 0h
>
> Currently, ReduceExpressionsRule.FILTER_INSTANCE can successfully reduce a query like this one (see RelOptRulesTest#testReduceConstantsDup):
> {code}
> // 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=[[]])
> {code}
> 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:
> {code}
> // 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]])
> {code}



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