[CALCITE-5032] The unexpected behavior on method RelOptUtil#splitJoinCondition

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.31.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Benchao Li
• Reporter: luoyuxia
• Created: 04/Mar/22 09:37
• Updated: 19/Aug/22 04:05
• Resolved: 15/Apr/22 00:06

Description

When I call the method

RexNode splitJoinCondition(
      List<RelDataTypeField> sysFieldList,
      List<RelNode> inputs,
      RexNode condition,
      List<List<RexNode>> joinKeys,
      @Nullable List<Integer> filterNulls,
      @Nullable List<SqlOperator> rangeOp)

, and the passed `joinKeys` is list with size 2, `condition` is like "1 = 1", then I found the `joinKeys` passed dosen't change as expected.

For the `joinKeys`, the first list will contain two RexNodes, and the second list contains no RexNode. I think the expected behavior should be the first list contain one RexNode, and the second contain one RexNode too.

After I dive into the code, I found such code will be invoked:

if ((rangeOp == null)
          && ((leftKey == null) || (rightKey == null))) {
        // no equality join keys found yet:
        // try transforming the condition to
        // equality "join" conditions, e.g.
        //     f(LHS) > 0 ===> ( f(LHS) > 0 ) = TRUE,
        // and make the RHS produce TRUE, but only if we're strictly
        // looking for equi-joins
        final ImmutableBitSet projRefs = InputFinder.bits(condition);
        leftKey = null;
        rightKey = null;

        boolean foundInput = false;
        for (int i = 0; i < inputs.size() && !foundInput; i++) {
          if (inputsRange[i].contains(projRefs)) {
            leftInput = i;
            leftFields = inputs.get(leftInput).getRowType().getFieldList();

            leftKey = condition.accept(
                new RelOptUtil.RexInputConverter(
                    rexBuilder,
                    leftFields,
                    leftFields,
                    adjustments));

            rightKey = rexBuilder.makeLiteral(true);

            // effectively performing an equality comparison
            kind = SqlKind.EQUALS;

            foundInput = true;
          }
        }
      }

It'll set `leftKey` and `righeKey`, but it won't set `rightInput`. So `rightInput` will be 0.
Then it'll try to add `leftKey` and `righeKey` to `joinKeys`,

addJoinKey(
            joinKeys.get(leftInput),
            leftKey,
            (rangeOp != null) && !rangeOp.isEmpty());
addJoinKey(
            joinKeys.get(rightInput),
            rightKey,
(rangeOp != null) && !rangeOp.isEmpty());

But the `rightInput` is 0, so the first list of `joinKeys` will be also add `righeKey`.

Could anyone please help me? Is it a bug or I misunderstand something? Thanks very much.

Issue Links

• links to: GitHub Pull Request #2756