Andrew Dunstan <andrew@dunslane.net> writes:
> In experimenting I needed to set this at 20 for it to bite much. If we
> wanted to fine tune it I'd be inclined to say that we wanted
> 20*connections buffers for the first, say, 50 or 100 connections and 10
> or 16 times for each connection over that. But that might be getting a
> little too clever - something we should leave to a specialised tuning
> tool. After all, we try these in fairly discrete jumps anyway. Maybe a
> simple factor around 20 would be sufficient.
I was thinking of a linear factor plus clamps to minimum and maximum
values --- does that make it work any better?
> Leaving aside the question of max_connections, which seems to be the
> most controversial, is there any objection to the proposal to increase
> the settings tried for shared_buffers (up to 4000) and max_fsm_pages (up
> to 200000) ? If not, I'll apply a patch for those changes shortly.
You probably need to fix the max-connections pass so that it applies the
same changes to max_fsm_pages as the second pass does --- otherwise, its
assumption that shared_buffers can really be set that way will be wrong.
Other than that I didn't see any problem with the shared_buffers part of
the patch.
regards, tom lane
