code: func createPerfSchemaTable(meta *model.TableInfo) *perfSchemaTable {
  	columns := make([]*table.Column, 0, len(meta.Columns))
  	for _, colInfo := range meta.Columns {
  		col := table.ToColumn(colInfo)
  		columns = append(columns, col)
  	}
  	t := &perfSchemaTable{
  		meta: meta,
  		cols: columns,
  	}
  	return t
  }
docs: // createPerfSchemaTable creates all perfSchemaTables