code: func (f *Field) SetCacheSize(v uint32) error {
  	f.mu.Lock()
  	defer f.mu.Unlock()
  
  	// Ignore if no change occurred.
  	if v == 0 || f.options.CacheSize == v {
  		return nil
  	}
  
  	// Persist meta data to disk on change.
  	f.options.CacheSize = v
  	if err := f.saveMeta(); err != nil {
  		return errors.Wrap(err, "saving")
  	}
  
  	return nil
  }
docs: // SetCacheSize sets the cache size for ranked fames. Persists to meta file on update.
  // defaults to DefaultCacheSize 50000