public void deleteMeasurement(long deletedNum) {
    measurementNumber.addAndGet(-deletedNum);
    schemaEngineStatistics.deleteMeasurement(deletedNum);
  }
This class is used to record statistics within the SchemaRegion in Memory mode.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/rescon/MemSchemaRegionStatistics.java