Re: max_connections/shared_buffers (was Re: Beta4 Tag'd and Bundled ...)

Greg Stark <gsstark(at)mit(dot)edu> writes:
> Perhaps the shared_buffers should only be set to 50% of the maximum size
> probed?

I think it's reasonable to expect the DBA to make any adjustments needed
for changes in environment. Partly this is because I don't see any
defensible way to do otherwise --- your 50% slop figure is without
foundation in terms of what might really be going on --- and partly
because we'd be handicapping ourselves unnecessarily if there *aren't*
any subsequent changes in environment.

On machines where shared memory actually gets used for anything by
default, I think that the default limits are likely to be fairly sane.
If shared memory is tight, then very likely Postgres is the only thing
on the machine that's going to want it. We might as well use what we
can get.

regards, tom lane