This is a follow up to one of my previous postings: Python and the Oracle Client. The main databases here are being upgraded to Oracle 12 and I’ve taken the opportunity to update the client used by my Python scripts, also its good practice to install new clients when old versions go out of support.

Current Setup

The system I am upgrading here has the following configuration, but this should work with any RPM based distribution, such as CentOS and SUSE :

• Red Hat Enterprise Linux Server release 6.6 (Santiago)
• Python 2.6.6
• python connector: cx_Oracle – 5.1.2
• oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64
• oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64

To find the versions of your currently installed software:
$ python
Python 2.6.6 (r266:84292, Nov 21 2013, 10:50:32)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cx_Oracle
>>> print cx_Oracle.version
5.1.2
and the Oracle client:
$ rpm -qa | grep oracle
oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64
oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64

Preparing

If you have the old versions installed you will need to do some tidying up by removing the client and python connector, version 11 of the client despite being RPM packaged had some non-standard elements. Use rpm to delete the old version of instant client, remove devel first:
$ sudo su
# rpm -ev oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64
# rpm -ev oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64

you may also need to remove the library reference from a previous installation:
# rm /etc/ld.so.conf.d/oracle.conf
# ldconfig
to remove the Python oracle connector, there are two methods. Manually, by finding the previously installed package deleting the files and editing the package list:
# find / -name cx_Oracle.py -print
/usr/lib/python2.6/site-packages/cx_Oracle-5.1.2-py2.6-linux-x86_64.egg/cx_Oracle.py
# cd /usr/lib/python2.6/site-packages
# rm -rf cx_Oracle-5.1.2-py2.6-linux-x86_64.egg

now edit the easy-install.pth file
# nano /usr/lib/python2.6/site-packages/easy-install.pth
and remove the line:
./cx_Oracle-5.1.2-py2.6-linux-x86_64.egg

Or do it the easy way, if you have pip installed:
# sudo pip uninstall cx_Oracle
easy_install does not have an uninstall option.

Installing

Download and install version 12 of the Instant Client and SDK (devel), these can be gotten from: http://www.oracle.com/technetwork/database/features/instant-client/index-097480.html For Linux choose the correct flavour for your installed operating system: x86 or x86-64 for 64bit operating systems, you will need to register on the site gain access the files.
# rpm -i oracle-instantclient12.1-basic-12.1.0.2.0-1.x86_64.rpm
# rpm -i oracle-instantclient12.1-devel-12.1.0.2.0-1.x86_64.rpm
Now to install the python connector:
# easy_install cx-Oracle
or, the recommended method:
# pip install cx-Oracle
Installation for the version 12 client is much more straight forward than that for version 11.

Testing

A quick test to ensure that the expected versions appear, and that you can connect to the database.
Python 2.6.6 (r266:84292, Nov 21 2013, 10:50:32)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cx_Oracle
>>> cx_Oracle.version
'5.2'
>>> oraConn = "<USERNAME>/<PASSWORD>@<DATABASE HOST>:<DATABASE PORT>/<SERVICE>"
>>> ocDB = cx_Oracle.connect(oraConn)
>>> ocDB.version
'12.1.0.2.0'


Sources

• https://bitbucket.org/anthony_tuininga/cx_oracle

Update 24 Nov 2015: Also, see my post Upgrading the Python Oracle Client for updating from version 11 to 12.

Installing the python cx_Oracle extension module for connecting to Oracle databases on this Fedora 18 workstation turned out to be a bit of a faff by giving an assortment of unhelpful error messages, if you are having the same pain maybe this will help.

You will need two files from the Oracle Database Instant Client download site, the basic client package and the SDK (devel): http://www.oracle.com/technetwork/database/features/instant-client/index-097480.html For Linux choose the correct flavour for your installed operating system: x86 or x86-64 for 64bit operating systems, you will need to register on the site to access the files. For my purposes I got the 11.2 version for x64 RPM files, install them using:
$ sudo rpm -i oracle-instantclient11.2-basic-11.2.0.3.0-1.x86_64.rpm
$ sudo rpm -i oracle-instantclient11.2-devel-11.2.0.3.0-1.x86_64.rpm
You will now need to tell the system where the libraries are:
$ sudo su
# echo /usr/lib/oracle/11.2/client64/lib/ > /etc/ld.so.conf.d/oracle.conf
# ldconfig
# exit
To install cx_Oracle you will need to set some environment variables otherwise you will get an “error: cannot locate an Oracle software installation” message. The easy_install program is found in python-setuptools I have included it in the recipe as a reminder if you have not installed it already.
$ sudo yum install python-setuptools
$ export ORACLE_HOME=/usr/lib/oracle/11.2/client64
$ export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH
$ export PATH=$ORACLE_HOME/bin:$PATH
$ sudo -E easy_install cx_Oracle
or by downloading the version from http://cx-oracle.sourceforge.net/ and installing it manually, you will still need to set the exports, as above, and do the following for installation:
$ sudo -E python setup.py build
$ sudo -E python setup.py install
The -E on the sudo takes your environment variables, including the three you just set, into your sudo session.

Success:
$ python
Python 2.7.3 (default, Aug 9 2012, 17:23:57)
[GCC 4.7.1 20120720 (Red Hat 4.7.1-5)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cx_Oracle
>>> exit()

When the the library cannot be seen, you get this error:
$ python
Python 2.7.3 (default, Aug 9 2012, 17:23:57)
[GCC 4.7.1 20120720 (Red Hat 4.7.1-5)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import cx_Oracle
Traceback (most recent call last):
File "", line 1, in
ImportError: libclntsh.so.11.1: cannot open shared object file: No such file or directory
>>> exit()