@Override
    public Void visitCall(RexCall call) {
      if (res) {
        res = validRexCall(call);
        if (res) {
          return super.visitCall(call);
        }
      }
      return null;
    }
A utility class that helps identify Hive-Jdbc functions gaps.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/jdbc/JDBCRexCallValidator.java