I haven't done any testing yet (but I will). Our situation is that we were running Oracle 8i on Linux and decided to switch to PostgreSQL 7.0.2. Currently, BOTH are running. With 3 developers beating on the machine (they use emacs), X, and a couple setiathome processes (grin) running, the machine is still quite speedy and is easily the fastest Linux box I've played on to date.
specs:
Supermicro P6DGS dual slot1 motherboard
2 x P3-850 SECC2 coppermines
1gig SDRAM (2 x 512mb ECC SDRAM)
3 x 9gig Quantum Atlas V 7200 drives (software RAID 0)
integrated dual channel Adaptec U2W controller
cheesy Netgear FA310X ethernet card
matrox G400 video
Redhat 6.2
I even configured it with a 2gig swapfile (per Oracle's recommendation). I've yet to witness it swap.
Cheers,
Chris
