@Override
    public String toString() {
      if (dirs.size() == 1) {
        return ETLSplitStrategy.class.getSimpleName() + " strategy for " + dirs.get(0).dir;
      } else {
        StringBuilder sb = new StringBuilder(ETLSplitStrategy.class.getSimpleName()
            + " strategy for ");
        boolean isFirst = true;
        for (ETLDir dir : dirs) {
          if (!isFirst) sb.append(", ");
          isFirst = false;
          sb.append(dir.dir);
        }
        return sb.toString();
      }
    }
ETL strategy is used when spending little more time in split generation is acceptable
(split generation reads and caches file footers).
ql/src/java/org/apache/hadoop/hive/ql/io/orc/OrcInputFormat.java