I wrote:
>Tom Lane said:
>
>
>>I think this probably needs to be more aggressive
>>though. In a
>>situation of limited SHMMAX it's probably more important to keep
>>shared_buffers as high as we can than to get a high max_connections. We
>>could think about increasing the 5x multiplier, adding Min and/or Max
>>limits, or some combination.
>>
>>
>>
>
>Yes. If we were to base it on the current maxima (1000/100), we could use a
>factor of 10, or if on the maxima I am now proposing (4000/250) a factor of
>16. Something in that range is about right I suspect.
>
>
>
>
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.
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.
cheers
andrew