Re: Postgres performance comments from a MySQL user

Kaarel <kaarel@future.ee> writes:
> This makes me wonder why is the default configuration so conservative?

There are still a lot of platforms where desirable settings will cause
the database to fail to start, because the default kernel limits on
shared memory are still set for 1980s-vintage hardware.

We have had a policy for a long time that we'd rather the out-of-the-box
settings be guaranteed to start than that they be optimal for
performance.  No one is going to get as far as testing performance
if the system won't start for them.

Having said that, though, I do wonder whether we couldn't bump them up a
little.  Are there still any live platforms where the default SHMMAX is
less than 4 MB?  (There was discussion of this a month or two back on
pghackers, but no conclusion.)

            regards, tom lane