@TestOnly
  void reset() throws IOException {
    if (!directory.exists()) {
      return;
    }
    File[] ratioFiles = directory.listFiles((dir, name) -> name.startsWith(FILE_PREFIX));
    if (ratioFiles == null) {
      return;
    }
    for (File file : ratioFiles) {
      Files.delete(file.toPath());
    }
    totalMemorySize = new AtomicLong(0);
    totalDiskSize = 0L;
  }
Restore compression ratio statistics from disk when system restart
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/flush/CompressionRatio.java