Installing PostgreSQL 8.4 (and or MySQL 5) on Snow Leopard 10.6 and RVM

Wow, this is really a nasty one, but here’s how to ease the pain:

1) do yourself a huge favor, get macports, it will install ALL the dependencies it needs for an installation

2) sudo port install mysql5-server
sudo port install postgresql84-server

3) Setup you Server:
sudo mkdir -p /opt/local/var/db/postgresql84/defaultdb
sudo chown postgres:postgres /opt/local/var/db/postgresql84/defaultdb
sudo su postgres -c '/opt/local/lib/postgresql84/bin/initdb -D /opt/local/var/db/postgresql84/defaultdb'

Setup Postgres to auto-run as a server on start up:

sudo launchctl load -w /Library/LaunchDaemons/org.macports.postgresql84-server.plist

Start the Server:
sudo su postgres -c '/opt/local/lib/postgresql84/bin/postgres -D /opt/local/var/db/postgresql84/defaultdb'
4) add the pg_config path to your path mate .bashrc

should be similar to:
export PATH="/opt/local/bin:/opt/local/sbin:/opt/local/lib/postgresql84/bin:/usr/local/bin:/usr/local:$PATH"

5) since 10.6 is a 32-64bit System for top performance add this to your .bashrc file (it will help with installing the gem later)
export ARCHFLAGS='-arch x86_64'

6) Add the Path to the RVM Config
mate ~/.rvm/config/db

at the bottom:
system_path=/opt/local/bin:/opt/local/sbin:/opt/local/lib/postgresql84/bin/:/usr/local/lib:/usr/local/bin:/usr/local:/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11/bin


7) Switch to the ruby version you want with rvm rvm use 1.8.7

8) Source the .bashrc => source ~/.bashrc

9) Install the gem
gem install pg (no sudo!!!)

Done

it took me 3 hours to set it up, what a pain!!!
I will post the procedure for 1.9.1 in a comment to this post