code: func dbFetchIndexerTip(dbTx database.Tx, idxKey []byte) (*chainhash.Hash, int32, error) {
  	indexesBucket := dbTx.Metadata().Bucket(indexTipsBucketName)
  	serialized := indexesBucket.Get(idxKey)
  	if len(serialized) < chainhash.HashSize+4 {
  		return nil, 0, database.Error{
  			ErrorCode: database.ErrCorruption,
  			Description: fmt.Sprintf("unexpected end of data for "+
  				"index %q tip", string(idxKey)),
  		}
  	}
  
  	var hash chainhash.Hash
  	copy(hash[:], serialized[:chainhash.HashSize])
  	height := int32(byteOrder.Uint32(serialized[chainhash.HashSize:]))
  	return &hash, height, nil
  }
docs: // dbFetchIndexerTip uses an existing database transaction to retrieve the
  // hash and height of the current tip for the provided index.