code: func (h *Handle) GetPartitionStats(tblInfo *model.TableInfo, pid int64) *statistics.Table {
  	tbl, ok := h.StatsCache.Load().(StatsCache)[pid]
  	if !ok {
  		tbl = statistics.PseudoTable(tblInfo)
  		tbl.PhysicalID = pid
  		h.UpdateTableStats([]*statistics.Table{tbl}, nil)
  		return tbl
  	}
  	return tbl
  }
docs: // GetPartitionStats retrieves the partition stats from cache.