iPhoto 9.6 - how to request all photos in a a given album

In a Ruby script I access the iPhoto database, I get a root_folder uuid from the RKFolder in the Library.apdb :

 @root_folder_uuid = @db.execute("SELECT uuid FROM RKFolder table
 WHERE name = '#{@config["root_folder"]}' 
 AND  parentFolderUuid = 'TopLevelAlbums' ").flatten.first

then using this root uuid , I get get all albums uuid within the root folder, from the RKAlbum in the Library.apdb :

albums = @db.execute("SELECT uuid, name  FROM RKAlbum table
WHERE folderUuid = '#{@root_folder_uuid}' 
AND albumSubclass = 3 ")

Now , I need to get all photos within each album... when i look at the RKMaster table (where all photos records are stored) .. I don't see what is the relationship attribute between a photo record and an album....

any hints ? thanks for help