public static void deleteRedundantFilesByIndex(File[] files, int index) throws IOException {
    for (int i = 0; i < files.length; i++) {
      if (i != index) {
        Files.delete(files[i].toPath());
      }
    }
  }
Restore compression ratio statistics from disk when system restart
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/flush/CompressionRatio.java