[CALCITE-988] FilterToProjectUnifyRule.invert(MutableRel, MutableRel, MutableProject) works incorrectly

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.6.0
• Assignee: Wei Xue
• Reporter: Wei Xue
• Created: 23/Nov/15 15:34
• Updated: 21/Jan/16 22:20
• Resolved: 23/Nov/15 20:22

Description

The below code does not "invert" but only projects what's been projected. A type mismatch exception would be thrown when creating the new MutableProject.

      for (Ord<RexNode> expr : Ord.zip(project.getProjects())) {
        if (expr.e instanceof RexInputRef) {
          final int target = ((RexInputRef) expr.e).getIndex();
          exprList.set(expr.i,
              rexBuilder.ensureType(expr.e.getType(),
                  RexInputRef.of(target, input.rowType),
                  false));
        } else {
          throw MatchFailed.INSTANCE;
        }
      }

However, the exposure of this bug is quite low. Actually I couldn't find a query that would go through this code path, coz looks like any query that has a Filter will have a Project on top of that, which makes it go the other branch and use the other invert() method. A filtered view will produce a Filter on top of another Filter thus can reproduce this problem.