code: func (h *Handle) FlushStats() {
  	for len(h.ddlEventCh) > 0 {
  		e := <-h.ddlEventCh
  		if err := h.HandleDDLEvent(e); err != nil {
  			logutil.Logger(context.Background()).Debug("[stats] handle ddl event fail", zap.Error(err))
  		}
  	}
  	if err := h.DumpStatsDeltaToKV(DumpAll); err != nil {
  		logutil.Logger(context.Background()).Debug("[stats] dump stats delta fail", zap.Error(err))
  	}
  	if err := h.DumpStatsFeedbackToKV(); err != nil {
  		logutil.Logger(context.Background()).Debug("[stats] dump stats feedback fail", zap.Error(err))
  	}
  }
docs: // FlushStats flushes the cached stats update into store.