Upgrading Postgres.app

Migrating to Postgres 9.2 takes some command line acrobatics.

Published on December 21, 2012.


Heroku recently unveiled support for Postgres 9.2, offering performance improvements and several new features. Before migrating our production database at Jobber, we want to run it in development for a few days.

I’ve been using Postgres.app on my Mac for a while now. Patches are seamless, but migrating from 9.1 to 9.2 takes some command line acrobatics. The documentation sets you on the right track, but I ran into a few gotchas.

These instructions are for upgrading to Version (20). If you have a newer version, things may have improved!

  1. Keep your old copy of Postgres.app, you’ll need it. After Quitting, move it to the desktop.
  2. Download the new version of Postgres.app and install it to Applications.
  3. Launch the new version of Postgres. You need the right-click+open trick on Mountain Lion to get around Gatekeeper. It will move your old database files to a var-9.1 folder and initialize a new database in its place.
  4. Fiddle in psql to prepare the new database (see below).
  5. Quit out of Postgres.app and perform the upgrade.

Database already exists

My first attempt failed.

The new data files already had a nathany database (my username), so pg_upgrade couldn’t create it. I’m sure there are a few ways to solve this problem, depending on whether or not you want to migrate this database or discard it. Let’s keep it.

We’ll need to use psql with the new Postgres.app running. Here are a few helpful Meta-Commands:

Command What it does
\l list databases (press q to return to the prompt)
\c name switch databases (connect)
\q quit

It won’t DROP a database while connected to it, so I ended up creating a new temporary database. Use a name that won’t cause conflicts:

nathany=# CREATE DATABASE temporary_database;
nathany=# \c temporary_database
You are now connected to database "temporary_database" as user "nathany".
temporary_database=# DROP DATABASE nathany;
temporary_database=# \q

Substitute nathany for your username.


Now we can quit Postgres.app and run the upgrade. It requires absolute paths, so you must substitute ~/ for the path to your user folder (eg. /Users/nathany/).

pg_upgrade --old-datadir "~/Library/Application Support/Postgres/var-9.1"
           --new-datadir "~/Library/Application Support/Postgres/var"
           --old-bindir "~/Desktop/Postgres.app/Contents/MacOS/bin"
           --new-bindir "/Applications/Postgres.app/Contents/MacOS/bin"

This assumes that the new version of Postgres.app is in Applications and the old version is on your Desktop.


You can fire up Postgres.app and psql to drop that temporary database:

nathany=# DROP DATABASE temporary_database;
nathany=# \q

When the upgrade completes, it suggests you run:


So do that. And finally, you can delete the old version of Postgres.app. Phew!

That’s A Wrap

You can follow Postgres.app on Twitter to find out when you get to do this all over again. :-)

Now all I have left to do is find a nice database client for Postgres. It looks like the two new candidates are Tuples 2 and Induction (very alpha), though Navicat has been steadily improving as well. Hmm.

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Nathan Youngman

Software Developer and Author