[
https://issues.apache.org/jira/browse/CALCITE-3198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16885912#comment-16885912
]
Ruben Quesada Lopez commented on CALCITE-3198:
----------------------------------------------
[~julianhyde], you are right. I talked about {{ReduceExpressionsRule}} because
it seemed to me the "entry point" of this issue. However, in the end this rule
delegates much of the reduction process to {{RexSimplify}}, so I guess that is
where we should act to fix this.
> ReduceExpressionsRule.FILTER_INSTANCE does not reduce 'NOT(x=a AND x=b)'
> ------------------------------------------------------------------------
>
> Key: CALCITE-3198
> URL: https://issues.apache.org/jira/browse/CALCITE-3198
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.20.0
> Reporter: Ruben Quesada Lopez
> Priority: Minor
>
> 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, filter removed):
> LogicalProject(DEPTNO=[$0])
> LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
> {code}
> Since the filter is the negated of an 'always false filter' (the one used in
> the previous query), it is therefore an 'always true filter', so the expected
> behavior is that the LogicalFilter should be removed, and it is not.
--
This message was sent by Atlassian JIRA
(v7.6.14#76016)
