[CALCITE-2675] Type validation error as ReduceExpressionRule fails to preserve type nullability

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.18.0
• Assignee: Zoltan Haindrich
• Reporter: Zoltan Haindrich
• Created: 15/Nov/18 16:18
• Updated: 27/Feb/24 22:23
• Resolved: 19/Nov/18 20:44

Description

If a simplification could happen after some ReduceExpression rewrite; the simplification result may have a slightly different type in nullability.

  @Test public <T> void testReduceCaseNullabilityChange() throws Exception {
    HepProgram program = new HepProgramBuilder()
        .addRuleInstance(ReduceExpressionsRule.FILTER_INSTANCE)
        .addRuleInstance(ReduceExpressionsRule.PROJECT_INSTANCE)
        .build();

    try (Hook.Closeable a = Hook.REL_BUILDER_SIMPLIFY.add(Hook.propertyJ(false))) {
      checkPlanning(program,
          "select case when empno = 1 then 1 when 1 IS NOT NULL then 2 else null end as qx "
              + "from emp");
    }

Exposed by CALCITE-1413 changes; I'm not sure if there is any other variations for which the same could happen.

Issue Links

• causes: CALCITE-2687 Is distinct from could lead to Exceptions in ReduceExpressionRule
• relates to: HIVE-20913 Narrowing nullability may cause typecheck failures
• links to: PR922