[CALCITE-2466] RexSimplify incorrectly simplify conjunction statement with null literal

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Invalid
• Fix Version/s: 1.18.0
• Component/s: core
• Assignee: Julian Hyde
• Reporter: Shuyi Chen
• Created: 14/Aug/18 06:52
• Updated: 16/Aug/18 15:17
• Resolved: 16/Aug/18 15:17

Description

This can be reproduced using the following test:

 @Test public void testFilterReduction() throws Exception {
    HepProgramBuilder programBuilder = HepProgram.builder();
    programBuilder.addRuleInstance(ReduceExpressionsRule.FILTER_INSTANCE);
    HepPlanner planner = new HepPlanner(programBuilder.build());
    final String sql = "select deptno from dept_nested where NAME <> '' AND employees <> null";
    planner.setRoot(tester.convertSqlToRel(sql).rel);
    RelNode bestRel = planner.findBestExp();

    assertEquals(
        "LogicalProject(DEPTNO=[$0])\n" +
        "  LogicalFilter(condition=[AND(<>($1, ''), <>($3, null))])\n" +
        "    LogicalTableScan(table=[[CATALOG, SALES, DEPT_NESTED]])\n",
        RelOptUtil.toString(bestRel));
  }

In this test,

NAME <> '' AND employees <> null

is always evaluated to false incorrectly, so the optimized plan is

LogicalProject(DEPTNO=[$0])
  LogicalValues(tuples=[[]])

.