Yeah, eventually adding some level of understanding of the formats would be nice, but honestly my immediate need is a higher-performance (and somewhat specialized) replication solution; I only need a tiny bit of understanding of the data I'm shipping from server to server. But at the same time, a complete solution would need to deal with all three formats and the numerous flavors thereof, not just CSV. I don't doubt that the current FromField/ToField interface isn't particularly well suited to dealing with copy data, though. =) As for threadWaitWrite, I understand that, but the code is actually dead code at the moment because postgresql-simple doesn't use libpq connections in asynchronous mode; it's just there for when postgresql-simple starts using async libpq calls. Which is something I would like to do, but it would also be a disaster on Windows at the moment. I'm thinking perhaps that the most sensible thing to do would be to reimplement the blocking libpq calls in haskell using nonblocking libpq calls, and then only use this module on unix systems. Hopefully that would cut down on the CPP hackery.