public Boolean execute(CompactorContext input) throws IOException, HiveException, InterruptedException {
    return compactor.run(input);
  }
Runs different compactions based on the order in which compactors are added.<br>
Mainly used for fall back mechanism for Merge compaction.
ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/CompactorPipeline.java