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https://issues.apache.org/jira/browse/CALCITE-5646?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17712458#comment-17712458
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Leonid Chistov edited comment on CALCITE-5646 at 4/14/23 6:51 PM:
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[~julianhyde]
I am not sure that this a bug in Strong.
I think that following thing had happened:
* Strong class had a Javadoc comment "A predicate is strong (or
null-rejecting) if it is UNKNOWN if *any* of its inputs is UNKNOWN."
* Actual implementation of class methods works different way:
** {{public static boolean isStrong(RexNode e)}} method checks whether it is
true, that if we set *all* inputs to UNKNOWN, we will get UNKNOWN as the
expression result
** Other methods that accept explicit set of inputs via bitset, check whether
it is true, that if we set *all* inputs *from specified set* to UNKNOWN, we
will get UNKNOWN as the expression result
* It seems that JoinDeriveIsNotNullFilterRule assumed behavior described in
Javadoc, but not the real one
was (Author: JIRAUSER298393):
[~julianhyde]
I am not sure that this a bug in Strong.
I think that following thing had happened:
* Strong class had a Javadoc comment "A predicate is strong (or
null-rejecting) if it is UNKNOWN if *any* of its inputs is UNKNOWN."
* Actual implementation of class methods works different way:
** {\{public static boolean isStrong(RexNode e)}} method checks whether it is
true, that if we set *all* inputs to UNKNOWN, we will get UNKNOWN as the
expression result
** Other methods that accept explicit set of inputs via bitset, check whether
it is true, that if we set *all* inputs from specified bit set to UNKNOWN, we
will get UNKNOWN as the expression result
* It seems that JoinDeriveIsNotNullFilterRule assumed behavior described in
Javadoc, but not the real one
> JoinDeriveIsNotNullFilterRule incorrectly handles COALESCE in join condition
> ----------------------------------------------------------------------------
>
> Key: CALCITE-5646
> URL: https://issues.apache.org/jira/browse/CALCITE-5646
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.34.0
> Reporter: Leonid Chistov
> Assignee: Leonid Chistov
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Consider query
> {code:java}
> select t1.deptno from empnullables t1 inner join
> empnullables t2 on coalesce(t1.ename, t2.ename) = 'abc' {code}
> When JoinDeriveIsNotNullFilterRule is applied to it, it is incorrectly
> transformed to query plan
> {code:java}
> LogicalProject(DEPTNO=[$7])
> LogicalJoin(condition=[=(CASE(IS NOT NULL($1), $1, $10), 'abc')],
> joinType=[inner])
> LogicalFilter(condition=[IS NOT NULL($1)])
> LogicalTableScan(table=[[CATALOG, SALES, EMPNULLABLES]])
> LogicalFilter(condition=[IS NOT NULL($1)])
> LogicalTableScan(table=[[CATALOG, SALES, EMPNULLABLES]]) {code}
> It is not valid to deduce that join keys from the both sides cannot have null
> values. All that we can deduce from the join condition, is that they cannot
> be null in the same time.
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