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https://issues.apache.org/jira/browse/CALCITE-5732?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17728105#comment-17728105
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Ruben Q L commented on CALCITE-5732:
------------------------------------
[~viggoc] just to confirm: the bug occurs with both HashJoin and MergeJoin, but
only when the join condition is composite (if it is simple, then nulls are
correctly handled)?
> EnumerableJoin should not return rows matching condition 'null = null'
> ----------------------------------------------------------------------
>
> Key: CALCITE-5732
> URL: https://issues.apache.org/jira/browse/CALCITE-5732
> Project: Calcite
> Issue Type: Bug
> Components: linq4j
> Reporter: Viggo Chen
> Priority: Major
> Fix For: 1.35.0
>
>
> In `EnumerableJoinTest#testMergeJoinWithCompositeKeyAndNullValues`, the query
> is like
> {code:java}
> select
> emps.empid
> from
> emps a join emps b
> on a.deptno = b.deptno
> and a.commission = b.commission;{code}
> and the data is like
> {code:java}
> INSERT INTO "emps" VALUES (100, 10, 'Bill', 10000, 1000);
> INSERT INTO "emps" VALUES (200, 20, 'Eric', 8000, 500);
> INSERT INTO "emps" VALUES (150, 10, 'Sebastian', 7000, null);
> INSERT INTO "emps" VALUES (110, 10, 'Theodore', 11500, 250); {code}
> And row with empid = 150 is in expected result. Is this the expected result
> of join with null condition.
> Whats more hash join result with condition a.deptno = b.deptno and
> a.commission = b.commission is same as merge join. And if there is just one
> condition a.commission = b.commission, the result do not include empid = 150.
>
> Here is a unit test for it
> {code:java}
> @Test void testHashJoinWithCompositeKeyAndNullValues() {
> // Both join side 'commission' a limited to null, so a.commission =
> b.commission should always be false.
> // So all columns in right table b are expected to be null, this sql should
> result in 0 rows.
> final String sql = "select * from\n"
> + " (select empid, salary, commission from emps where commission is
> null) as a\n"
> + " left join\n"
> + " (select empid, salary, commission from emps where commission is
> null) as b\n"
> + " on a.salary = b.salary and a.commission = b.commission\n"
> + " where b.empid is not null";
> CalciteAssert.that()
> .with(CalciteConnectionProperty.LEX, Lex.JAVA)
> .with(CalciteConnectionProperty.FORCE_DECORRELATE, false)
> .withSchema("s", new ReflectiveSchema(new HrSchemaBig()))
> .query(sql)
> .withHook(Hook.PLANNER, (Consumer<RelOptPlanner>) planner -> {
> planner.removeRule(EnumerableRules.ENUMERABLE_JOIN_RULE);
> planner.addRule(EnumerableRules.ENUMERABLE_MERGE_JOIN_RULE);
> })
> .explainContains("EnumerableHashJoin")
> .returnsCount(0)
> ;
> } {code}
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