code: func (c cache) removeDeletedBindMeta(hash string, meta *BindMeta) {
  	metas, ok := c[hash]
  	if !ok {
  		return
  	}
  
  	for i := len(metas) - 1; i >= 0; i-- {
  		if meta.isSame(meta) {
  			metas = append(metas[:i], metas[i+1:]...)
  			if len(metas) == 0 {
  				delete(c, hash)
  				return
  			}
  		}
  	}
  }
docs: // removeDeletedBindMeta removes all the BindMeta which originSQL and db are the same with the parameter's meta.