public boolean isEmpty() {
    return totalMemTableSize == 0
        && (workMemTable == null || workMemTable.getTotalPointsNum() == 0);
  }
Return Long.MAX_VALUE if workMemTable is null
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/storageengine/dataregion/memtable/TsFileProcessor.java