Install postgresql using homebrew on OSX

If there's existing postgres install,

brew rm postgresql --force

Else

brew update
brew install postgres

Then follow instructions on printed by homebrew

initdb /usr/local/var/postgres
cp /usr/local/Cellar/postgresql/9.1.4/homebrew.mxcl.postgresql.plist ~/Library/LaunchAgents/
launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.postgresql.plist
pg_ctl -D /usr/local/var/postgres -l /usr/local/var/postgres/server.log start