[CALCITE-3828] MergeJoin throws NPE in case of null keys

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.21.0
• Fix Version/s: 1.23.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Ruben Q L
• Reporter: Ruben Q L
• Created: 26/Feb/20 09:11
• Updated: 24/May/20 11:59
• Resolved: 06/Mar/20 09:11

Description

Problem can be reproduced with the following test (to be added to EnumerablesTest.java):

@Test public void testMergeJoinWithNullKeys() {
  assertThat(
  EnumerableDefaults.mergeJoin(
    Linq4j.asEnumerable(
      Arrays.asList(
        new Emp(30, "Fred"),
        new Emp(20, "Sebastian"),
        new Emp(30, "Theodore"),
        new Emp(20, "Theodore"),
        new Emp(40, null),
        new Emp(30, null))),
    Linq4j.asEnumerable(
      Arrays.asList(
        new Dept(15, "Marketing"),
        new Dept(20, "Sales"),
        new Dept(30, "Theodore"),
        new Dept(40, null))),
    e -> e.name,
    d -> d.name,
    (v0, v1) -> v0 + ", " + v1, false, false).toList().toString(),
  equalTo("[Emp(30, Theodore), Dept(30, Theodore),"
    + " Emp(20, Theodore), Dept(30, Theodore)]"));
}

which throws a NPE inside EnumerableDefaults#MergeJoinEnumerator when trying to compare null keys:

java.lang.NullPointerException
	at java.lang.String.compareTo(String.java:1155)
	at java.lang.String.compareTo(String.java:111)
	at org.apache.calcite.linq4j.EnumerableDefaults$MergeJoinEnumerator.advance(EnumerableDefaults.java:3861)

Issue Links

• links to: GitHub Pull Request #1833