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SEMI JOIN should not duplicate a singleton left row #5241

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SEMI JOIN should not duplicate a singleton left row #5241

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2 changes: 2 additions & 0 deletions core/src/main/java/org/apache/calcite/rel/rules/SingleValuesOptimizationRules.java
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Original file line number Diff line number Diff line change
Expand Up @@ -284,8 +284,10 @@ static Predicate<Join> isJoinTransformable(boolean isLeft) {
|| jn.getJoinType() == JoinRelType.FULL;

if (isLeft) {
// A semi join must emit the left row only once, even if several right rows match.
return jn -> !(jn.getJoinType() == JoinRelType.LEFT
|| jn.getJoinType() == JoinRelType.LEFT_MARK
|| jn.getJoinType() == JoinRelType.SEMI
|| isFullOrAntiJoin.test(jn));
} else {
return jn -> !(jn.getJoinType() == JoinRelType.RIGHT || isFullOrAntiJoin.test(jn));
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21 changes: 21 additions & 0 deletions core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java
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Expand Up @@ -5625,6 +5625,27 @@ RelOptFixture checkDynamicFunctions(boolean treatDynamicCallsAsConstant) {
.check();
}

@Test void testSemiJoinWithConstantRowOnLeft() {
relFn(builder -> builder
.values(new String[]{"l"}, 1)
.values(new String[]{"r"}, 1, 1)
.semiJoin(builder.equals(builder.field(2, 0, 0), builder.field(2, 1, 0)))
.build())
.withRule(SingleValuesOptimizationRules.JOIN_LEFT_INSTANCE)
.checkUnchanged();
}

@Test void testSemiJoinWithProjectOnConstantRowOnLeft() {
relFn(builder -> builder
.values(new String[]{"l"}, 1)
.projectPlus(builder.call(SqlStdOperatorTable.CURRENT_TIMESTAMP))
.values(new String[]{"r"}, 1, 1)
.semiJoin(builder.equals(builder.field(2, 0, 0), builder.field(2, 1, 0)))
.build())
.withRule(SingleValuesOptimizationRules.JOIN_LEFT_PROJECT_INSTANCE)
.checkUnchanged();
}

@Test void testRightJoinWithConstantRowOnLeft() {
final String sql = "select e.empno, e.ename, c.*"
+ " from (select 5 as nm) c right join emp e on e.empno = c.nm";
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19 changes: 19 additions & 0 deletions core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
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Expand Up @@ -18935,6 +18935,25 @@ LogicalProject(DEPTNO=[$0])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalProject(ACCTNO=[$0])
LogicalTableScan(table=[[CATALOG, CUSTOMER, ACCOUNT]])
]]>
</Resource>
</TestCase>
<TestCase name="testSemiJoinWithConstantRowOnLeft">
<Resource name="planBefore">
<![CDATA[
LogicalJoin(condition=[=($0, $1)], joinType=[semi])
LogicalValues(tuples=[[{ 1 }]])
LogicalValues(tuples=[[{ 1 }, { 1 }]])
]]>
</Resource>
</TestCase>
<TestCase name="testSemiJoinWithProjectOnConstantRowOnLeft">
<Resource name="planBefore">
<![CDATA[
LogicalJoin(condition=[=($0, $2)], joinType=[semi])
LogicalProject(l=[$0], $f1=[CURRENT_TIMESTAMP])
LogicalValues(tuples=[[{ 1 }]])
LogicalValues(tuples=[[{ 1 }, { 1 }]])
]]>
</Resource>
</TestCase>
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