public static String getLogSuffix(CompactionTaskType type) {
    String logNameSuffix = null;
    switch (type) {
      case INNER_SEQ:
      case INNER_UNSEQ:
      case REPAIR:
        logNameSuffix = INNER_COMPACTION_LOG_NAME_SUFFIX;
        break;
      case CROSS:
        logNameSuffix = CROSS_COMPACTION_LOG_NAME_SUFFIX;
        break;
      case INSERTION:
        logNameSuffix = INSERTION_COMPACTION_LOG_NAME_SUFFIX;
        break;
      case SETTLE:
        logNameSuffix = SETTLE_COMPACTION_LOG_NAME_SUFFIX;
        break;
      default:
        break;
    }
    return logNameSuffix;
  }
MergeLogger records the progress of a merge in file "merge.log" as text lines.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/compaction/execute/utils/log/CompactionLogger.java