> If you have PostgreSQL or MySQL on the same machine as your application, you can use UNIX sockets; they won't have much latency at all (I think Linux also optimizes TCP on localhost to skip all the pointless protocol overhead).
Sounds like a nice topic for a study; I'd expect the latency using local sockets to connect to a DB server to be about 3x as much, minimum, as the latency to simply write to a file.
Writing to a file: a single context-switch from process to kernel (CS).
Writing to a socket: CS on write to socket, CS when receiving process writes the data to file, CS when receiving process sends ACK to sender via a socket.
The worst thing you can do in your program is to cause a context switch by passing data to kernel or recieving data from a kernel.
That being said, a trial of the two approaches is not a bad idea for an easily-publishable paper :-)
