AcidDirectory getDirInfo() {
      return dirInfo;
    }
Returns the virtual columns needed for update queries. For ACID queries it is a single ROW__ID, for non-native
tables the list is provided by the {@link HiveStorageHandler#acidVirtualColumns()}.
@param table The table for which we run the query
@return The list of virtual columns used
ql/src/java/org/apache/hadoop/hive/ql/io/AcidUtils.java