Re: shared memory on OS X - 7.4beta4

Slightly off topic confirmations...

>>> And here are are the default settings for OS X 10.2.6:
>>>
>>> sysctl -w kern.sysv.shmmax=4194304

Seems to be the default on 10.2.8 as well.

10.1.5 doesn't seem to have a kern.sysv.* section:

[broccoli:~] erics% sysctl kern.sysv.shmmax
second level name sysv in kern.sysv.shmmax is invalid

>>
>> Well, I can only say that if I lower shmmax to that value, initdb
>> picks
>> max_connections = 50
>> shared_buffers = 300
>
> I just did a fresh install of 7.4b5 on a fresh install of MacOS 10.3,
> and initdb
> picked those same values for postgresql.conf. PostgreSQL started up
> the first
> time successfully, but then refused to start again even after
> restarting the
> computer until I reduced shared_buffers.

I've had cases in 10.1.x where after hammering on the database for a
while and having to restart it, there was no longer enough shared
memory to start postgres, requiring a restart of the computer. On 10.1,
I couldn't even get it to change the shmmax value, necessitating some
very low buffer numbers (nearly out of the box for pg 7.2, yes, that
bad).

eric