Tomas Kovarik and I have presented at PGCon 2007 in Ottawa the ideas about other possible optimizer algorithms to be used in PostgreSQL.
We are quite new to PostgreSQL project so it took us some time to go through the sources end explore the possibilities how things could be implemented.
There is a proposal attached to this mail about the interface we would like to implement for switching between different optimizers. Please review it and provide a feedback to us. Thank You.