public static File[] findCompactionLogs(boolean isInnerSpace, String directory) {
    File timePartitionDir = new File(directory);
    if (timePartitionDir.exists()) {
      return timePartitionDir.listFiles(
          (dir, name) -> {
            if (isInnerSpace) {
              return name.endsWith(INNER_COMPACTION_LOG_NAME_SUFFIX);
            } else {
              return name.endsWith(CROSS_COMPACTION_LOG_NAME_SUFFIX)
                  || name.endsWith(INSERTION_COMPACTION_LOG_NAME_SUFFIX);
            }
          });
    } else {
      return new File[0];
    }
  }
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