[CALCITE-3979] Simplification might have removed CAST expression(s) incorrectly

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.22.0
• Fix Version/s: 1.23.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Zoltan Haindrich
• Reporter: Shuo Cheng
• Created: 08/May/20 07:25
• Updated: 10/Jul/20 19:35
• Resolved: 14/May/20 07:55

Description

@Test public void testCastRemove() throws Exception {
  final String sql = "select\n" +
      "case when cast(ename as double) < 5 then 0.0\n" +
      "     else coalesce(cast(ename as double), 1.0)\n" +
      "     end as t\n" +
      " from (\n" +
      "       select\n" +
      "          case when ename > 'abc' then ename\n" +
      "               else null\n" +
      "               end as ename from emp\n" +
      " )";
  sql(sql).withRule(ReduceExpressionsRule.PROJECT_INSTANCE).check();
}

As shown in the above test case, `cast(ename as double) < 5` was reduced as `ename < 5` when reducing expression, which lead to the following exception:

java.math.BigDecimal cannot be cast to org.apache.calcite.util.NlsStringjava.math.BigDecimal cannot be cast to org.apache.calcite.util.NlsStringjava.lang.ClassCastException: java.math.BigDecimal cannot be cast to org.apache.calcite.util.NlsString at org.apache.calcite.util.NlsString.compareTo(NlsString.java:47) at com.google.common.collect.Range.compareOrThrow(Range.java:672) at com.google.common.collect.Cut.compareTo(Cut.java:79) at com.google.common.collect.Range.isConnected(Range.java:526) at org.apache.calcite.rex.RexSimplify.residue(RexSimplify.java:1702) at org.apache.calcite.rex.RexSimplify.simplifyUsingPredicates(RexSimplify.java:1636) at org.apache.calcite.rex.RexSimplify.simplifyComparison(RexSimplify.java:451) at org.apache.calcite.rex.RexSimplify.simplifyComparison(RexSimplify.java:321) at org.apache.calcite.rex.RexSimplify.simplify(RexSimplify.java:292) at org.apache.calcite.rex.RexSimplify.simplifyAndTerms(RexSimplify.java:492) at org.apache.calcite.rex.RexSimplify.simplifyAnd(RexSimplify.java:1275) at org.apache.calcite.rex.RexSimplify.simplify(RexSimplify.java:264) at org.apache.calcite.rex.RexSimplify.simplifyCase(RexSimplify.java:992) at org.apache.calcite.rex.RexSimplify.simplify(RexSimplify.java:270) at org.apache.calcite.rex.RexSimplify.simplifyCase(RexSimplify.java:926) at org.apache.calcite.rex.RexSimplify.simplify(RexSimplify.java:270) at org.apache.calcite.rex.RexSimplify.simplifyUnknownAs(RexSimplify.java:235) at org.apache.calcite.rex.RexSimplify.simplifyPreservingType(RexSimplify.java:174) at org.apache.calcite.rel.rules.ReduceExpressionsRule.reduceExpressions(ReduceExpressionsRule.java:629) at org.apache.calcite.rel.rules.ReduceExpressionsRule$ProjectReduceExpressionsRule.onMatch(ReduceExpressionsRule.java:305) at org.apache.calcite.plan.AbstractRelOptPlanner.fireRule(AbstractRelOptPlanner.java:338)

Issue Links

• relates to: CALCITE-4118 RexSimplify might remove CAST from RexNode incorrectly
• links to: pr