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[CALCITE-7833] MULTI_JOIN_OPTIMIZE_BUSHY may turn an outer join into an inner join #5301

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Merged
zzwqqq merged 1 commit into from
Oct 10, 2026
+49 −10
Merged

[CALCITE-7833] MULTI_JOIN_OPTIMIZE_BUSHY may turn an outer join into an inner join #5301

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15 changes: 5 additions & 10 deletions core/src/main/java/org/apache/calcite/rel/rules/MultiJoinOptimizeBushyRule.java
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Original file line number Diff line number Diff line change
Expand Up @@ -104,16 +104,11 @@ public MultiJoinOptimizeBushyRule(RelFactories.JoinFactory joinFactory,
final RelMetadataQuery mq = call.getMetadataQuery();

final LoptMultiJoin multiJoin = new LoptMultiJoin(multiJoinRel);
for (int i = 0; i < multiJoin.getNumJoinFactors(); i++) {
ImmutableBitSet outerJoinFactors = multiJoin.getOuterJoinFactors(i);
if (outerJoinFactors == null) {
continue;
}
if (!outerJoinFactors.isEmpty()) {
// Refuse to apply this rule to a multijoin with outer joins,
// since this rule cannot handle outer joins.
return;
}

if (multiJoinRel.isFullOuterJoin() || multiJoinRel.containsOuter()) {
// Refuse to apply this rule to a multijoin with outer joins,

@zzwqqq zzwqqq Oct 4, 2026

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Does this rule rebuild all joins as INNER joins? If so, could you mention this in the comment?

@ehds ehds Oct 4, 2026 •
edited
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Yes. This rule rebuilds all join factors from LoptMultiJoin as INNER joins, so it cannot preserve outer-join semantics.
The issue was frist reported by https://issues.apache.org/jira/browse/CALCITE-5289

// since this rule cannot handle outer joins.
return;
}

final List<Vertex> vertexes = new ArrayList<>();
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18 changes: 18 additions & 0 deletions core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java
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Expand Up @@ -4656,6 +4656,24 @@ private void checkPushJoinThroughUnionOnRightDoesNotMatchSemiOrAntiJoin(JoinRelT
sql(sql).withPre(preProgram).withProgram(program).check();
}

/** Test case for <a href="https://issues.apache.org/jira/browse/CALCITE-7833">[CALCITE-7833]
* MULTI_JOIN_OPTIMIZE_BUSHY may turn an outer join into an inner join</a>. */
@Test void testBushyJoinRuleSkipsFullOuterJoin() {

@zzwqqq zzwqqq Oct 4, 2026

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Could you please add a comment referencing the jira above these test cases?

@ehds ehds Oct 4, 2026

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Added the Jira reference to these test cases.

sql("select * from emp full join dept on emp.deptno = dept.deptno")
.withPreRule(CoreRules.JOIN_TO_MULTI_JOIN)
.withRule(CoreRules.MULTI_JOIN_OPTIMIZE_BUSHY)
.checkUnchanged();
}

/** Test case for <a href="https://issues.apache.org/jira/browse/CALCITE-7833">[CALCITE-7833]
* MULTI_JOIN_OPTIMIZE_BUSHY may turn an outer join into an inner join</a>. */
@Test void testBushyJoinRuleSkipsLeftJoinOnTrue() {
sql("select * from emp left join dept on true")
.withPreRule(CoreRules.JOIN_TO_MULTI_JOIN)
.withRule(CoreRules.MULTI_JOIN_OPTIMIZE_BUSHY)
.checkUnchanged();
}

@Test void testConvertMultiJoinRule() {
final String sql = "select e1.ename from emp e1, dept d, emp e2\n"
+ "where e1.deptno = d.deptno and d.deptno = e2.deptno";
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26 changes: 26 additions & 0 deletions core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
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Expand Up @@ -1894,6 +1894,32 @@ LogicalProject(ENAME=[$1])
MultiJoin(joinFilter=[true], isFullOuterJoin=[false], joinTypes=[[INNER, LEFT]], outerJoinConditions=[[NULL, =($1, $10)]], projFields=[[ALL, ALL]])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
]]>
</Resource>
</TestCase>
<TestCase name="testBushyJoinRuleSkipsFullOuterJoin">
<Resource name="sql">
<![CDATA[select * from emp full join dept on emp.deptno = dept.deptno]]>
</Resource>
<Resource name="planBefore">
<![CDATA[
LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8], DEPTNO0=[$9], NAME=[$10])
MultiJoin(joinFilter=[=($7, $9)], isFullOuterJoin=[true], joinTypes=[[INNER, INNER]], outerJoinConditions=[[NULL, NULL]], projFields=[[ALL, ALL]])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
]]>
</Resource>
</TestCase>
<TestCase name="testBushyJoinRuleSkipsLeftJoinOnTrue">
<Resource name="sql">
<![CDATA[select * from emp left join dept on true]]>
</Resource>
<Resource name="planBefore">
<![CDATA[
LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8], DEPTNO0=[$9], NAME=[$10])
MultiJoin(joinFilter=[true], isFullOuterJoin=[false], joinTypes=[[INNER, LEFT]], outerJoinConditions=[[NULL, true]], projFields=[[ALL, ALL]])
LogicalTableScan(table=[[CATALOG, SALES, EMP]])
LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
]]>
</Resource>
</TestCase>
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