agree a key would be a good idea. hmm, right now in the case where an original post does not have any syndication urls, I store original=permalink, syndication=None to avoid refetching it every time we process the h-feed ... couple ideas:

1. a compound key of the two properties
2. or, only store non-null SyndicatedPost -> non-null OriginalPost relationships in the database, and remember "recently searched syndicated posts" and "recently searched permalinks" to the cache.