Andras Fabian <Fabian@atrada.net> writes:
>> Something weird about the network stack on the new machine, maybe.
>> Have you compared the transfer speeds for Unix-socket and TCP connections?
> Hmm, no ... but how do Unix-socket / TCP connections relate to STDOUT here (sorry, maybe this is obvious to some, but
notto me at the moment)?
Well, COPY TO STDOUT really means "send the data across the network
connection to the client". It sounds to me like your problem is slow
data transfer between the database backend and pg_dump (or psql).
Not sure what could be causing it, unless perhaps you've got a kernel
packet filter that's performing an unreasonable amount of processing
per packet.
regards, tom lane