Kasia Tuszynska <ktuszynska@esri.com> wrote:
> We are configuring Postgres on Ubuntu
> Nothing but Postgres will be running on the machine. I have read
> that we should assign twice the available RAM to swap, that seems
> like a lot.
I remember years ago reading that if swap space was twice RAM, that
Linux could use a different algorithm for swapping, which was
generally expected to be faster. I don't know whether that is still
true.
> Would Postgres ever use so much space?
It could, in certain conditions, but you would probably not like the
performance. You're best off avoiding overcommitting memory to that
extent.
> Any recommendations or best practices?
I would follow the general recommendations for the OS, and worry
about tuning PostgreSQL memory usage so that you don't drive
anything significant into swap space. On our production systems we
generally see a very small amount swapped out fairly early which
doesn't grow and is never swapped back in. I suspect it is
OS-related code which we're not using.
-Kevin