public static String[] getReadColumnNames(Configuration conf) {
    String colNames = conf.get(READ_COLUMN_NAMES_CONF_STR, READ_COLUMN_IDS_CONF_STR_DEFAULT);
    if (colNames != null && !colNames.isEmpty()) {
      return colNames.split(conf.get(serdeConstants.COLUMN_NAME_DELIMITER, String.valueOf(SerDeUtils.COMMA)));
    }
    return new String[] {};
  }
Returns an array of column ids(start from zero) which is set in the given
parameter <pre>conf</pre>.
serde/src/java/org/apache/hadoop/hive/serde2/ColumnProjectionUtils.java