At the time of writing this book, OpenShift supports two versions of the PostgreSQL database. You can view all the supported PostgreSQL versions by running the following command:
$ rhc cartridges|grep postgresql postgresql-8.4 PostgreSQL 8.4 addon postgresql-9.2 PostgreSQL 9.2 addon
In this recipe, you will learn how to add the PostgreSQL 9.2 cartridge to your OpenShift application.
To complete this recipe, you will need the rhc command-line client installed on your machine. Please refer to the Installing the OpenShift rhc command-line client recipe in Chapter 1, Getting Started with OpenShift, for details. Also, we will use the application created in the Creating an OpenShift application using the rhc command-line client recipe in Chapter 3, Creating and Managing Applications.