Re: max_fsm_pages increase

On Sun, Oct 31, 2010 at 4:43 AM, AI Rumman <rummandba(at)gmail(dot)com> wrote:
> I using Postgresql 8.1 and during vacuum at night time, I am getting the
> following log:
> number of page slots needed (2520048) exceeds max_fsm_pages (356656)
> Do I need to increase max_fsm_pages to 2520048? Does it have any bad affect?

You don't *have* to do it. The consequences of not doing it are: 1)
your server will not know all of the pages in the files holding your
database that there are empty slots available for use. 2) because of
that lack of knowledge, it may then allocate new pages to hold your
data, causing potentially more bloat, and the need for even more FSM
pages. 3) Allocating new pages usually costs more than just filling
in space on existing page, so your system slows down.

If I were you, I'd set the FSM pages to double what your current need
is, run vacuum again, and you should be good for a while. It will
unfortunately, require a restart of your postgres server.