Qing Zhao <qzhao@quotefx.net> writes:
> We have got a G5 64-bit processor to replace an old G4 32-bit
> processor. Given everything else equal, should we see a big
> improvement on PG's performance?
Nope. Database performance typically depends on disk performance first,
and RAM size second. A 64-bit processor might help by allowing you to
install more RAM, but you didn't say that you had.
> The other question I have is that, when I tried different size for
> shared_buffer ( i used 10,000, 1,000, 528, 256) and Max
> connections=32, it gives me error when I tried to start PG using
> pg_ctl start as postgres. It kept saying this is bigger than the
> system Shared Memory.
Out-of-the-box, Mac OS X has a very low SHMMAX limit. See the PG admin
docs or the mail list archives about how to increase it. You should do
this --- most people find that you want to set shared_buffers to 1000 or
10000 or so for best performance.
regards, tom lane