Preparing an Oracle test setup

This document is work in progress

This document attempt to ease the task of running the Django (or your own app's) test suite against Oracle by:

• Providing a step by step setup guide to achieve that.
• Hopefully collecting information (best practices, tuning tips) to do that as efficiently as possible.

Chosen components are:

• Oracle XE (10g)
• GNU/Debian Linux. Things should also work with Ubuntu Linux without too much tweaking.

The system isn't going to be dedicated exclusively to run Oracle so we will leave things set up so it is necessary to start it manually before a test-debug session.

Obtain and install Oracle XE

We will be roughly following the Oracle installation documentation.

1. Download the oracle-xe-universal_10.2.0.1-1.0_i386.deb package file from http://www.oracle.com/technetwork/database/express-edition/downloads/index.html (Oracle Database 10g Express Edition for Linux x86). You need to have an Oracle Developer Network account. Contrarily to what is suggested in some places I've found the newer .deb package you can get here and installable by using high level Debian/Ubuntu package management tools (APT, Aptitude, ...) didn't install things like the /etc/init.d/oracle-xe init script and some files under the /usr/lib/oracle hierarchy so I went with the older package plus the low-level dpkg package manager and taking care of dependencies manually (see next step).

2. Install the prerequisite packages, if you fail to do so the installation won't be successful but won't abort either:

   $ sudo apt-get install bc libaio1
   

3. Make sure you have enough swap space. If you fail to do this, the Oracle package installation will abort with an error message about this unmet condition.

   RAM [MiB]	Swap size required
   0 > RAM >= 256	3 * RAM
   256 > RAM > 512	2 * RAM
   RAM >= 512	1 GiB

4. Install the package you downloaded:

   $ sudo dpkg -i oracle-xe-universal_10.2.0.1-1.0_i386.deb
   

5. Configure the DB engine:

   $ sudo /etc/init.d/oracle-xe configure
   

   It will ask you a number of questions, namely:

   • A TCP port for the Oracle Database XE graphical user interface (default: 8080)
   • A TCP port for the Oracle database listener (default: 1521)
   • A password for the SYS and SYSTEM administrative user accounts. Take note of the value you choose.
   • Whether you want the database to start automatically when the computer starts -- I chose NO here, see next step.

6. Optional -- Create an alternate init script -- If you've answered NO to the question about running the Oracle DB engine automatically on system start then it won't be possible to start it manually because that flag is stored (among others) in the /etc/default/oracle-xe configuration file and we would be using the same script as the one executed when the system boots (the SyV /etc/init.d/oracle-xe script) that always examines these values.

   What we can do is to create a slightly modified /etc/init.d/xe script that ignores that flag and allows us to control the Oracle process at will:

   $ cd /etc/init.d
   $ sudo cp -a oracle-xe xe
   $ sudo patch < /home/myuser/oracle-xe-script.diff
   

   This is the oracle-xe-script.diff patch file (you can also download it):

   --- xe   2006-02-24 17:23:15.000000000 -0300
   +++ xe.new  2010-11-03 07:58:43.000000000 -0300
   @@ -596,13 +596,8 @@
    # See how we were called
    case "$1" in
      start)
   -       if test -f "$CONFIGURATION"
   +       if test ! -f "$CONFIGURATION"
           then
   -               if test "$ORACLE_DBENABLED" != "true"
   -               then
   -                       exit 0
   -               fi
   -       else
           echo "Oracle Database 10g Express Edition is not configured.  You must run
   '/etc/init.d/oracle-xe configure' as the root user to configure the database."
                   exit 0
   @@ -613,13 +608,8 @@
           configure
           ;;
      stop)
   -       if test -f "$CONFIGURATION"
   +       if test ! -f "$CONFIGURATION"
           then
   -               if test "$ORACLE_DBENABLED" != "true"
   -               then
   -                       exit 0
   -               fi
   -       else
           echo "Oracle Database 10g Express Edition is not configured.  You must run
   '/etc/init.d/oracle-xe configure' as the root user to configure the database."
                   exit 0
   

   Now we can start/stop Oracle manually using it:

   $ sudo /etc/init.d/xe start
   Starting Oracle Net Listener.
   Starting Oracle Database 10g Express Edition Instance.
   
   $ sudo /etc/init.d/xe stop
   Shutting down Oracle Database 10g Express Edition Instance.
   Stopping Oracle Net Listener.
   

   (in newer versions of Debian/Ubuntu we can use the shorter version sudo service xe start)

7. Make sure the Oracle environment vars needed by its client libraries are set (Bash shell):

   $ echo "source /usr/lib/oracle/xe/app/oracle/product/10.2.0/server/bin/oracle_env.sh" >> ~/.bashrc
   $ source /usr/lib/oracle/xe/app/oracle/product/10.2.0/server/bin/oracle_env.sh
   

8. Decide if you will perform the following two tasks

   • Access the administrative web app
   • Run the Django tests

   from the same system as the DB engine or from another system through the network. If you chose the first option we are done, if you chose the second option for any of the two kinds of access then you need to solve the following two issues first (see the Oracle installation documentation for detailed instructions):

   • You will need to install the Oracle client stack.
   • By default no access of any type (SQL sessions, admin web app) is allowed through the network to the DB engine, you need to change that by using the administrative web interface or possibly using the sqlplus tool.

9. Access the DB engine administration web app by pointing our Web browser to http://localhost:8080/apex and using the SYSTEM user plus the password you chose above.

10. Create an user to be used to connect to the DB when running the tests. (e.g. djangotest) -- Go to Home > Administration > Database Users > CREATE assign it a password (e.g. foo)

11. Give the user the needed privileges.

    • Roles: CONNECT, RESOURCE and DBA

Install cx_Oracle

$ sudo apt-get install python-dev

$ sudo pip install cx_Oracle

or:

$ sudo easy_install cx_Oracle

etc.

Create the Django settings file

$ cat oracle.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': 'xe',
        'USER': 'djangotest',
        'PASSWORD': 'tehsekret',
        'TEST_USER': 'django_test_default',
        'TEST_TBLSPACE': 'django_test_default',
        'TEST_TBLSPACE_TMP': 'django_test_default_temp',
    },

    'other': {
        'ENGINE': 'django.db.backends.oracle',
        'NAME': 'xe',
        'USER': 'djangotest',
        'PASSWORD': 'tehsekret',
        'TEST_USER': 'django_test_other',
        'TEST_TBLSPACE': 'django_test_other',
        'TEST_TBLSPACE_TMP': 'django_test_other_temp',
    },
}

The key is that NAME should be the same ('xe') for both entries, since you're really establishing two connections to the same database. The TEST_USER, TEST_TBLSPACE, and TEST_TBLSPACE_TMP entries must be different, however. Thanks Ian Kelly for providing the correct settings file.

Test things

$ sudo /etc/init.d/xe start

$ ./runtests --settings=oracle.py basic

Creating test database 'default'...
Creating test user...
Creating test database 'other'...
Creating test user...
.......s...
----------------------------------------------------------------------
Ran 11 tests in 2.279s

OK (skipped=1)
Destroying test database 'default'...
Destroying test user...
Destroying test database tables...
Destroying test database 'other'...
Destroying test user...
Destroying test database tables...

Notes

In my particular case I've implemented this setup by using a KVM virtual machine (host system is a workstation running Debian unstable Sid). The VM got two CPUs, 1 GiB of RAM and a 30 GiB hard disk. Platform is GNU/Debian Linux 5.0 aka Lenny (stable as of Nov 2010) because it still is in its support period and as a bonus contains Python 2.4 in pre-packaged form.

Things to review:

• How much does the Oracle installation pollutes the system?. If it result to be confined and easy to undo/cleanup, maybe this setup doesn't need to be done inside a VM.
• System resource (CPU, RAM usage while running the full test suite). Maybe I can reduce the RAM assigned to the VM to 512 MiB and the virtual CPU count from two to one.