cx_Oracle 6 Installation

Overview

To use cx_Oracle 6 with Python and Oracle Database you need:

  • Python 2.7 or 3.4 and higher. Older versions of cx_Oracle may work with older versions of Python.
  • Oracle client libraries. These can be from the free Oracle Instant Client, or those included in Oracle Database if Python is on the same machine as the database. Oracle client libraries versions 12.2, 12.1 and 11.2 are supported on Linux, Windows and macOS. Users have also reported success with other platforms.
  • An Oracle Database. Oracle’s standard client-server version interoperability allows cx_Oracle to connect to both older and newer databases.

Quick Start cx_Oracle Installation

  • An installation of Python is needed. Python 2.7 and Python 3.4 and higher are supported by cx_Oracle 6.

  • Install cx_Oracle from PyPI with:

    python -m pip install cx_Oracle --upgrade
    

    Note: if a binary wheel package is not available for your platform, the source package will be downloaded instead. This will be compiled and the resulting binary installed.

  • Add Oracle 12.2, 12.1 or 11.2 client libraries to your operating system library search path such as PATH on Windows or LD_LIBRARY_PATH on Linux. On macOS move the files to ~/lib or /usr/local/lib.

    • If your database is remote, then download and unzip the client libraries from the free Oracle Instant Client “Basic” or “Basic Light” package for your operating system architecture.

      Instant Client on Windows requires an appropriate Microsoft Windows Redistributables. On Linux, the libaio (sometimes called libaio1) package is needed.

    • Alternatively use the client libraries already available in a locally installed database such as the free Oracle XE release.

    Version 12.2 client libraries can connect to Oracle Database 11.2 or greater. Version 12.1 client libraries can connect to Oracle Database 10.2 or greater. Version 11.2 client libraries can connect to Oracle Database 9.2 or greater.

  • After installation, your Python applications will be able to connect to your database. The database can be on the same machine as Python, or on a remote machine. cx_Oracle does not install or create a database.

    You will need to know user credentials and the connection string for the database.

    You can learn how to use cx_Oracle from the API documentation and samples.

If you run into trouble, check out the section on Troubleshooting.

The database abstraction layer in cx_Oracle is ODPI-C, which means that the ODPI-C installation instructions can be useful to review.

Oracle Client and Oracle Database Interoperability

cx_Oracle requires Oracle Client libraries. The libraries provide the necessary network connectivity to access an Oracle Database instance. They also provide basic and advanced connection management and data features to cx_Oracle.

The simplest way to get Oracle Client libraries is to install the free Oracle Instant Client “Basic” or “Basic Light” package. The libraries are also available in any Oracle Database installation or full Oracle Client installation.

Oracle’s standard client-server network interoperability allows connections between different versions of Oracle Client libraries and Oracle Database. For certified configurations see Oracle Support’s Doc ID 207303.1. In summary, Oracle Client 12.2 can connect to Oracle Database 11.2 or greater. Oracle Client 12.1 can connect to Oracle Database 10.2 or greater. Oracle Client 11.2 can connect to Oracle Database 9.2 or greater. The technical restrictions on creating connections may be more flexible. For example Oracle Client 12.2 can successfully connect to Oracle Database 10.2.

cx_Oracle uses the shared library loading mechanism available on each supported platform to load the Oracle Client libraries at runtime. It does not need to be rebuilt for different versions of the libraries. Since a single cx_Oracle binary can use different client versions and also access multiple database versions, it is important your application is tested in your intended release environments. Newer Oracle clients support new features, such as the oraaccess.xml external configuration file available with 12.1 or later clients, and session pool enhancements to dead connection detection in 12.2 clients.

The cx_Oracle function clientversion() can be used to determine which Oracle Client version is in use and the attribute Connection.version can be used to determine which Oracle Database version a connection is accessing. These can then be used to adjust application behavior accordingly. Attempts to use some Oracle features that are not supported by a particular client/server combination may result in runtime errors. These include:

  • when attempting to access attributes that are not supported by the current Oracle Client library you will get the error “ORA-24315: illegal attribute type”
  • when attempting to use implicit results with Oracle Client 11.2 against Oracle Database 12c you will get the error “ORA-29481: Implicit results cannot be returned to client”
  • when attempting to get array DML row counts with Oracle Client 11.2 you will get the error “DPI-1013: not supported”

Installing cx_Oracle on Linux

Install cx_Oracle

Use Python’s Pip package to install cx_Oracle from PyPI:

python -m pip install cx_Oracle --upgrade

This will download and install a pre-compiled binary if one is available for your architecture. If a pre-compiled binary is not available, the source will be downloaded, compiled, and the resulting binary installed. If you are using the default python package, you will need the python-devel package or equivalent, which provides the Python.h header file.

Install Oracle Client

Using cx_Oracle requires Oracle Client libraries to be installed. These provide the necessary network connectivity allowing cx_Oracle to access an Oracle Database instance. Oracle Client versions 12.2, 12.1 and 11.2 are supported.

  • If your database is remote, then download the free Oracle Instant Client “Basic” or “Basic Light” package for your operating system architecture. Use the RPM or ZIP packages, based on your preferences.
  • Alternatively use the client libraries already available in a locally installed database such as the free Oracle XE release.

Oracle Instant Client Zip Files

To use cx_Oracle with Oracle Instant Client zip files:

  1. Download an Oracle 11.2, 12.1 or 12.2 “Basic” or “Basic Light” zip file: 64-bit or 32-bit, matching your Python architecture.

  2. Unzip the package into a single directory that is accessible to your application. For example:

    mkdir -p /opt/oracle
    cd /opt/oracle
    unzip instantclient-basic-linux.x64-12.2.0.1.0.zip
    
  3. Install the libaio package with sudo or as the root user. For example:

    sudo yum install libaio
    

    On some Linux distributions this package is called libaio1 instead.

  4. If there is no other Oracle software on the machine that will be impacted, permanently add Instant Client to the runtime link path. For example, with sudo or as the root user:

    sudo sh -c "echo /opt/oracle/instantclient_12_2 > /etc/ld.so.conf.d/oracle-instantclient.conf"
    sudo ldconfig
    

    Alternatively, set the environment variable LD_LIBRARY_PATH to the appropriate directory for the Instant Client version. For example:

    export LD_LIBRARY_PATH=/opt/oracle/instantclient_12_2:$LD_LIBRARY_PATH
    
  5. If you intend to co-locate optional Oracle configuration files such as tnsnames.ora, sqlnet.ora or oraaccess.xml with Instant Client, then create a network/admin subdirectory. For example:

    mkdir -p /opt/oracle/instantclient_12_2/network/admin
    

    This is the default Oracle configuration directory for executables linked with this Instant Client.

    Alternatively, Oracle configuration files can be put in another, accessible directory. Then set the environment variable TNS_ADMIN to that directory name.

Oracle Instant Client RPMs

To use cx_Oracle with Oracle Instant Client RPMs:

  1. Download an Oracle 11.2, 12.1 or 12.2 “Basic” or “Basic Light” RPM: 64-bit or 32-bit, matching your Python architecture.

  2. Install the downloaded RPM with sudo or as the root user. For example:

    sudo yum install oracle-instantclient12.2-basic-12.2.0.1.0-1.x86_64.rpm
    

    Yum will automatically install required dependencies, such as libaio.

  3. If there is no other Oracle software on the machine that will be impacted, permanently add Instant Client to the runtime link path. For example, with sudo or as the root user:

    sudo sh -c "echo /usr/lib/oracle/12.2/client64/lib > /etc/ld.so.conf.d/oracle-instantclient.conf"
    sudo ldconfig
    

    Alternatively, set the environment variable LD_LIBRARY_PATH to the appropriate directory for the Instant Client version. For example:

    export LD_LIBRARY_PATH=/usr/lib/oracle/12.2/client64/lib:$LD_LIBRARY_PATH
    
  4. If you intend to co-locate optional Oracle configuration files such as tnsnames.ora, sqlnet.ora or oraaccess.xml with Instant Client, then create a network/admin subdirectory under lib/. For example:

    sudo mkdir -p /usr/lib/oracle/12.2/client64/lib/network/admin
    

    This is the default Oracle configuration directory for executables linked with this Instant Client.

    Alternatively, Oracle configuration files can be put in another, accessible directory. Then set the environment variable TNS_ADMIN to that directory name.

Local Database or Full Oracle Client

cx_Oracle applications can use Oracle Client 11.2, 12.1 or 12.2 libraries from a local Oracle Database or full Oracle Client installation.

The libraries must be either 32-bit or 64-bit, matching your Python architecture.

  1. Set required Oracle environment variables by running the Oracle environment script. For example:

    source /usr/local/bin/oraenv
    

    For Oracle Database XE, run:

    source /u01/app/oracle/product/11.2.0/xe/bin/oracle_env.sh
    
  2. Optional Oracle configuration files such as tnsnames.ora, sqlnet.ora or oraaccess.xml can be placed in $ORACLE_HOME/network/admin.

    Alternatively, Oracle configuration files can be put in another, accessible directory. Then set the environment variable TNS_ADMIN to that directory name.

Installing cx_Oracle on Windows

Install cx_Oracle

Use Python’s Pip package to install cx_Oracle from PyPI:

python -m pip install cx_Oracle --upgrade

This will download and install a pre-compiled binary if one is available for your architecture. If a pre-compiled binary is not available, the source will be downloaded, compiled, and the resulting binary installed.

Install Oracle Client

Using cx_Oracle requires Oracle Client libraries to be installed. These provide the necessary network connectivity allowing cx_Oracle to access an Oracle Database instance. Oracle Client versions 12.2, 12.1 and 11.2 are supported.

  • If your database is remote, then download the free Oracle Instant Client “Basic” or “Basic Light” package for your operating system architecture.
  • Alternatively use the client libraries already available in a locally installed database such as the free Oracle XE release.

Oracle Instant Client Zip Files

To use cx_Oracle with Oracle Instant Client zip files:

  1. Download an Oracle 11.2, 12.1 or 12.2 “Basic” or “Basic Light” zip file: 64-bit or 32-bit, matching your Python architecture.

  2. Unzip the package into a single directory that is accessible to your application, for example C:\oracle\instantclient_12_2.

  3. Set the environment variable PATH to include the path that you created in step 2. For example, on Windows 7, update PATH in Control Panel -> System -> Advanced System Settings -> Advanced -> Environment Variables -> System Variables -> PATH.

    Restart any open command prompt windows.

  4. If you intend to co-locate optional Oracle configuration files such as tnsnames.ora, sqlnet.ora or oraaccess.xml with Instant Client, then create a network\admin subdirectory, for example C:\oracle\instantclient_12_2\network\admin.

    This is the default Oracle configuration directory for executables linked with this Instant Client.

    Alternatively, Oracle configuration files can be put in another, accessible directory. Then set the environment variable TNS_ADMIN to that directory name.

  5. Oracle Instant Client libraries require the presence of the correct Visual Studio redistributable.

Local Database or Full Oracle Client

cx_Oracle applications can use Oracle Client 11.2, 12.1 or 12.2 libraries libraries from a local Oracle Database or full Oracle Client.

The Oracle libraries must be either 32-bit or 64-bit, matching your Python architecture.

  1. Set the environment variable PATH to include the path that contains OCI.dll, if it is not already set. For example, on Windows 7, update PATH in Control Panel -> System -> Advanced System Settings -> Advanced -> Environment Variables -> System Variables -> PATH.

    Restart any open command prompt windows.

  2. Optional Oracle configuration files such as tnsnames.ora, sqlnet.ora or oraaccess.xml can be placed in the network/admin subdirectory of the Oracle Database software installation.

    Alternatively, Oracle configuration files can be put in another, accessible directory. Then set the environment variable TNS_ADMIN to that directory name.

Installing cx_Oracle on macOS

Make sure you are not using the bundled Python. This has restricted entitlements and will fail to load Oracle client libraries. Instead use Homebrew or Python.org.

Install cx_Oracle

Use Python’s Pip package to install cx_Oracle from PyPI:

python -m pip install cx_Oracle --upgrade

The source will be downloaded, compiled, and the resulting binary installed.

Install Oracle Instant Client

cx_Oracle requires Oracle Client libraries, which are found in Oracle Instant Client for macOS. These provide the necessary network connectivity allowing cx_Oracle to access an Oracle Database instance. Oracle Client versions 12.2, 12.1 and 11.2 are supported.

To use cx_Oracle with Oracle Instant Client zip files:

  1. Download the 11.2, 12.1 or 12.2 “Basic” or “Basic Light” zip file from here. Choose either a 64-bit or 32-bit package, matching your Python architecture.

  2. Unzip the package into a single directory that is accessible to your application. For example:

    mkdir -p /opt/oracle
    unzip instantclient-basic-macos.x64-12.2.0.1.0.zip
    
  3. Add links to $HOME/lib or /usr/local/lib to enable applications to find the library. For example:

    mkdir ~/lib
    ln -s /opt/oracle/instantclient_12_2/libclntsh.dylib.12.1 ~/lib/
    

    Alternatively, copy the required OCI libraries. For example:

    mkdir ~/lib
    cp /opt/oracle/instantclient_12_2/{libclntsh.dylib.12.1,libclntshcore.dylib.12.1,libons.dylib,libnnz12.dylib,libociei.dylib} ~/lib/
    

    For Instant Client 11.2, the OCI libraries must be copied. For example:

    mkdir ~/lib
    cp /opt/oracle/instantclient_11_2/{libclntsh.dylib.11.1,libnnz11.dylib,libociei.dylib} ~/lib/
    
  4. If you intend to co-locate optional Oracle configuration files such as tnsnames.ora, sqlnet.ora or oraaccess.xml with Instant Client, then create a network/admin subdirectory. For example:

    mkdir -p /opt/oracle/instantclient_12_2/network/admin
    

    This is the default Oracle configuration directory for executables linked with this Instant Client.

    Alternatively, Oracle configuration files can be put in another, accessible directory. Then set the environment variable TNS_ADMIN to that directory name.

Install Using GitHub

In order to install using the source on GitHub, use the following commands:

git clone https://github.com/oracle/python-cx_Oracle.git cx_Oracle
cd cx_Oracle
git submodule init
git submodule update
python setup.py install

Note that if you download a source zip file directly from GitHub then you will also need to download an ODPI-C source zip file and extract it inside the directory called “odpi”.

Install Using Source from PyPI

The source package can be downloaded manually from PyPI and extracted, after which the following commands should be run:

python setup.py build
python setup.py install

Upgrading from cx_Oracle 5

If you are upgrading from cx_Oracle 5 note these installation changes:

  • When using Oracle Instant Client, you should not set ORACLE_HOME.
  • On Linux, cx_Oracle 6 no longer uses Instant Client RPMs automatically. You must set LD_LIBRARY_PATH or use ldconfig to locate the Oracle client library.
  • PyPI no longer allows Windows installers or Linux RPMs to be hosted. Use the supplied cx_Oracle Wheels instead.

Installing cx_Oracle 5.3

If you require cx_Oracle 5.3, download a Windows installer from PyPI or use python -m pip install cx-oracle==5.3 to install from source.

Very old versions of cx_Oracle can be found in the files section at SourceForce.

Troubleshooting

If installation fails:

  • Use option -v with pip. Review your output and logs. Try to install using a different method. Google anything that looks like an error. Try some potential solutions.
  • Was there a network connection error? Do you need to see the environment variables http_proxy and/or https_proxy?
  • Do you get the error “No module named pip”? The pip module is builtin to Python from version 2.7.9 but is sometimes removed by the OS. Use the venv module (builtin to Python 3.x) or virtualenv module (Python 2.x) instead.
  • Do you get the error “fatal error: dpi.h: No such file or directory” when building from source code? Ensure that your source installation has a subdirectory called “odpi” containing files. If missing, review the section on Install Using GitHub.

If importing cx_Oracle fails:

  • Do you get the error “DPI-1047: Oracle Client library cannot be loaded”?
    • Check that Python, cx_Oracle and your Oracle Client libraries are all 64-bit or all 32-bit. The DPI-1047 message will tell you whether the 64-bit or 32-bit Oracle Client is needed for your Python.
    • On Windows, restart your command prompt and use set PATH to check the environment variable has the correct Oracle Client listed before any other Oracle directories.
    • On Windows, use the DIR command on the directory set in PATH. Verify that OCI.DLL exists there.
    • On Windows, check that the correct Windows Redistributables have been installed.
    • On Linux, check the LD_LIBRARY_PATH environment variable contains the Oracle Client library directory.
    • On macOS, make sure Oracle Instant Client is in ~/lib or /usr/local/lib and that you are not using the bundled Python (use Homebrew or Python.org instead).
  • If you have both Python 2 and 3 installed, make sure you are using the correct python and pip (or python3 and pip3) executables.