Uninstalling Postgres

Dang! I lost the password to one of my Postgres installations. Fortunately, it had not been used so no great loss. But how to uninstall both the Postgres software, and the 'postgres' unix user on Mac OS X?

I found this posting telling me how to uninstall. I've written my own explanation below.

I did this with Postgres 9.0.4 with the Mac installer provided by EnterpriseDB, on Mac OS X 10.6.7 Snow Leopard.

The steps are:

1. Run the uninstaller app.
2. Delete the enclosing folder, and provide Mac system password to authorize deleting the 'data' folder.
3. Delete the 'postgres' Unix user.

Details

Run the uninstaller app installed as part of the Postgres package. However the uninstaller is not located in the Applications > PostgeSQL folder. Instead, look in the root folder (your hard disk) > Library > PostgreSQL > 9.0 > uinstall-postgresql.app. Running that app will remove all of Postgres except for two pieces:

• The folder enclosing the uninstaller, and the all-important "data" folder containing any databases you created.

The "data" folder is special because it belongs to the "postgres" Unix user created on your Mac during installation. So the admin Mac user in which you are using the Finder does not have direct access to that folder. Fortunately the regular admin Mac user can move that folder to the trash though you will be prompted for your Mac password.

• 'postgres' Unix user

Killing that Unix user, and its password, requires the use of Terminal.app found in the "Utilities" folder of the "Applications" folder.

Type the following into the Terminal:
    sudo dscl . delete /users/postgres

The 'sudo' means your are invoking special privileges as a system administrator. So you’ll be prompted to enter your Mac system password. The 'dscl' command works on Directory Service.

With that you are done. You may now reinstall Postgres. Only this time, write down your password in a safe place immediately, as I learned the hard way.

If for some reason you need/want to use the command line to unstall Postgres rather than the uninstaller app, see that posting link above.