optimize ram with go snippet 1

example1.go

// dataStore retrieves data
type dataStore interface {
    getData(context.Context, filter) ([]item, error)
}

// fileStorage uploads the data to file storage
type fileStorage interface {
    upload(context.Context, []byte) error
}

// run is the main logic of the service
func (s service) run(ctx context.Context, f filter) error {
    items, err := s.ds.getData(ctx, f)
    if err != nil {
        return fmt.Errorf("getting data: %v", err)
    }
    if err := s.up.upload(ctx, csvFrom(items)); err != nil {
        return fmt.Errorf("uploading: %v", err)
    }
    return nil
}

func csvFrom(items []item) []byte {
    // use encoding/csv package to serialize []item into []byte
}