@Override
  public long getMemorySize() {
    switch (type) {
      case INSERT_TABLET_NODE:
        return ((InsertNode) value).getMemorySize()
            / ((InsertTabletNode) value).getRowCount()
            * tabletInfo.getRangeRowCount();
      case INSERT_ROW_NODE:
      case INSERT_ROWS_NODE:
        return ((InsertNode) value).getMemorySize();
      case MEMORY_TABLE_SNAPSHOT:
        return ((IMemTable) value).getTVListsRamCost();
      case DELETE_DATA_NODE:
      case RELATIONAL_DELETE_DATA_NODE:
      case CONTINUOUS_SAME_SEARCH_INDEX_SEPARATOR_NODE:
      case MEMORY_TABLE_CHECKPOINT:
        return RamUsageEstimator.sizeOfObject(value);
      default:
        throw new RuntimeException("Unsupported wal entry type " + type);
    }
  }
This entry class stores info for persistence.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/wal/buffer/WALInfoEntry.java