My question is about setting the kernel shared memory for installing postgresql on mac osx 10.6.8. In the readme file of postgresql it is said:

Shared Memory

PostgreSQL uses shared memory extensively for caching and inter-process communication. Unfortunately, the default configuration of Mac OS X does not allow suitable amounts of shared memory to be created to run the database server.

Before running the installation, please ensure that your system is configured to allow the use of larger amounts of shared memory. Note that this does not 'reserve' any memory so it is safe to configure much higher values than you might initially need. You can do this by editting the file /etc/sysctl.conf - e.g.

% sudo vi /etc/sysctl.conf

On a MacBook Pro with 2GB of RAM, the author's sysctl.conf contains:

kern.sysv.shmmax=1610612736 kern.sysv.shmall=393216 kern.sysv.shmmin=1 kern.sysv.shmmni=32 kern.sysv.shmseg=8 kern.maxprocperuid=512 kern.maxproc=2048

Note that (kern.sysv.shmall * 4096) should be greater than or equal to kern.sysv.shmmax. kern.sysv.shmmax must also be a multiple of 4096.

Once you have edited (or created) the file, reboot before continuing with the installation. If you wish to check the settings currently being used by the kernel, you can use the sysctl utility:

% sysctl -a

The database server can now be installed.

I'm a real beginner with all this but need to instal postgresql for academic purposes do you know how i can set this kernel shared memory. Won't that be harmful for my system? Thank you in advance.

Matthieu