@Override
  public boolean equals(Object obj) {
    if (obj == this) {
      return true;
    }
    if (obj == null) {
      return false;
    }
    if (!(obj instanceof Checkpoint)) {
      return false;
    }
    Checkpoint other = (Checkpoint) obj;
    return this.type == other.type && Objects.equals(this.memTableInfos, other.memTableInfos);
  }
Checkpoint is the basic element of .checkpoint file, including type, number of memTables, and
brief information of each memTable.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/wal/checkpoint/Checkpoint.java