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https://issues.apache.org/jira/browse/CALCITE-7140?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Ruben Q L updated CALCITE-7140:
-------------------------------
Fix Version/s: 1.41.0
> Improve constant reduction of expressions containing SqlRowOperator
> -------------------------------------------------------------------
>
> Key: CALCITE-7140
> URL: https://issues.apache.org/jira/browse/CALCITE-7140
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Reporter: Ruben Q L
> Assignee: Ruben Q L
> Priority: Major
> Fix For: 1.41.0
>
>
> Currently, if we have a query like this (e.g. to be included in
> RelOptRulesTest):
> {code:java}
> @Test void testCardinality() {
> final String sql = "SELECT CARDINALITY(ARRAY[1, 2])";
> sql(sql).withRule(CoreRules.PROJECT_REDUCE_EXPRESSIONS).check();
> }
> {code}
> It is correctly reduced as "2" by the ReduceExpressionsRule:
> {code:xml}
> <TestCase name="testCardinality">
> <Resource name="sql">
> <![CDATA[SELECT CARDINALITY(ARRAY[1, 2])]]>
> </Resource>
> <Resource name="planBefore">
> <![CDATA[
> LogicalProject(EXPR$0=[CARDINALITY(ARRAY(1, 2))])
> LogicalValues(tuples=[[{ 0 }]])
> ]]>
> </Resource>
> <Resource name="planAfter">
> <![CDATA[
> LogicalProject(EXPR$0=[2])
> LogicalValues(tuples=[[{ 0 }]])
> ]]>
> </Resource>
> </TestCase>
> {code}
> However, a similar query containing constant structs:
> {code:java}
> @Test void testCardinalityWithRow() {
> final String sql = "SELECT CARDINALITY(ARRAY[ROW(1,'a'), ROW(2,'b')])";
> sql(sql).withRule(CoreRules.PROJECT_REDUCE_EXPRESSIONS).check();
> }
> {code}
> Is not reduced and remains unchanged:
> {code:xml}
> <TestCase name="testCardinalityWithRow">
> <Resource name="sql">
> <![CDATA[SELECT CARDINALITY(ARRAY[ROW(1,'a'), ROW(2,'b')])]]>
> </Resource>
> <Resource name="planBefore">
> <![CDATA[
> LogicalProject(EXPR$0=[CARDINALITY(ARRAY(ROW(1, 'a'), ROW(2, 'b')))])
> LogicalValues(tuples=[[{ 0 }]])
> ]]>
> </Resource>
> <Resource name="planAfter">
> <![CDATA[
> LogicalProject(EXPR$0=[2])
> LogicalValues(tuples=[[{ 0 }]])
> ]]>
> </Resource>
> </TestCase>
> =>
> org.opentest4j.AssertionFailedError: planAfter ==> expected: <
> LogicalProject(EXPR$0=[2])
> LogicalValues(tuples=[[{ 0 }]])
> > but was: <
> LogicalProject(EXPR$0=[CARDINALITY(ARRAY(ROW(1, 'a'), ROW(2, 'b')))])
> LogicalValues(tuples=[[{ 0 }]])
> {code}
> The reason is that in [ReduceExpressionsRule#ReducibleExprLocator a RexCall
> with SqlRowOperator is considered
> non-constant|https://github.com/apache/calcite/blob/3ceb364c158e80c59a89137c85637ad53f4c0fab/core/src/main/java/org/apache/calcite/rel/rules/ReduceExpressionsRule.java#L1150],
> since the "Row operator itself can't be reduced to a literal"; while this is
> true, in cases like this one, a RexCall (e.g. cardinality) containing a
> SqlRowOperator can be potentially reduced.
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