PostgreSQL on FreeBSD

[Lowell Gilbert]

I haven't used that software since it was called postgres, 
but I'll wade in anyway...

Wayne Pascoe <freebsd-questions at penguinpowered.org> writes:

> Hi all,
> 
> I'm trying to configure and tune postgresql on FreeBSD 4.9. We want to
> allow at least 128 concurrent connections but preferably 256. 
> 
> Looking at the documentation, we should be okay if we set the following
> in our kernel to achieve this:
> 
> kern.ipc.somaxconn = 512
> kern.ipc.shmall = 65536
> kern.ipc.shmmni = 128
> kern.ipc.semmni = 8
> kern.ipc.semmns = 256
> 
> Now, I have three questions...
> 
> 1. Why do we have to set these in the kernel ?

You don't.

>                                                Why does setting them in
> /etc/sysctl.conf or /etc/loader.conf not work ? 

You're doing something wrong.  That's all I can say when the
description of the failure is just "not work".

> 2. Is there a recommended list of settings that we should use in our
> kernel to allow 128 connections and 256 connections ? 

A single recommendation, no.  It's been discussed.  You started with
tuning(7), I assume.

> and lastly, 
> 
> 3. What is the impact on the rest of the system likely to be by setting
> aside this memory as shared memory ? Is it then no longer available to
> other applications like Apache and Exim ? Are there any other
> performance issues that we should be aware of ? 

Yes, the memory is pulled out of the general pool, and no, I don't
think there will be any other noticeable effects at those settings.