public boolean isDestToOpTypeInsertOverwrite(String clause) {
	if (destToOpType.containsKey(clause)) {
		return destToOpType.get(clause);
	} else {
	  return false;
	}
  }
Maping from table/subquery aliases to all the associated lateral view nodes.
ql/src/java/org/apache/hadoop/hive/ql/parse/QBParseInfo.java