private boolean skipFolding(JoinDesc joinDesc) {
      for (JoinCondDesc cond : joinDesc.getConds()) {
        if (cond.getType() == JoinDesc.INNER_JOIN || cond.getType() == JoinDesc.UNIQUE_JOIN
            || cond.getType() == JoinDesc.LEFT_SEMI_JOIN || cond.getType() == JoinDesc.ANTI_JOIN) {
          continue;
        }
        return true;
      }
      return false;
    }
Skip folding constants if there is outer join in join tree.
@param joinDesc
@return true if to skip.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/ConstantPropagateProcFactory.java