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Python cx_Oracle 5.3 for Oracle Database Released

Christopher Jones
Senior Principal Product Manager

Today we are pleased to announce the release of cx_Oracle 5.3, the extremely popular Python interface for Oracle Database. Binary and source bundles can be installed from PyPi, as normal.

cx_Oracle 5.3 works with Python version 2.7, and with versions 3.4 and higher. You can use cx_Oracle with Oracle 11.2, 12.1 and 12.2 client libraries, allowing connection to multiple Oracle Database versions. Oracle's standard client-server version interoperability allows connection to both older and newer databases. For example Oracle 11.2 client libraries can connect to Oracle Database 10.2 or later.

This release marks the move of the source code repository and home page to GitHub. User documentation remains on readthedocs. The cx_Oracle mail list also continues to operate, but you may find it easier to transition to GitHub for questions and issues.

The New cx_Oracle 5.3

Ever since Anthony Tuininga joined Oracle, he has been hard at work adding improvements to cx_Oracle. (He's also been laying the ground work for the next big release - more on that later in this post). I think you'll be impressed with cx_Oracle 5.3. At last year's Oracle OpenWorld, Anthony talked about some of the changes and got great positive feedback. Check out his presentation here.

This is a big update. While a few of the changes are specific to Oracle Database 12c features (see release notes), you will appreciate all the things that will make your applications better even if you have older databases. And you are upgrading to Oracle Database 12.2, right? Don't forget you can get immediate access to Oracle Database 12.2 using the Oracle Database Cloud.

Key New Features

  • Support for Python 3.6. Note Python versions earlier than 2.6 are no longer supported. (You can still get cx_Oracle 5.2 from PyPI, if you really need Python 2.6 support).

  • Support for Oracle client 12.2. Note Oracle clients earlier than 11.2 are no longer supported.

  • Direct binding to SQL objects. One great use case is binding Python objects to Oracle Spatial SDO objects. See InsertGeometry.py

  • PL/SQL records and collections can be bound. Interacting with PL/SQL stored logic has never been easier.

  • Support for scrollable cursors. Go back and forth through your query results. See ScrollableCursors.py

  • Support for Advanced Queuing. Use database notifications to build micro-service applications. See AdvancedQueuing.py

  • Fetch PL/SQL implicit results. Easily return query results from PL/SQL. See ImplicitResults.py

  • Transaction Guard support. Verify transaction status after unplanned server outages. See TransactionGuard.py

  • Support for Edition Based Redefinition. Easily switch applications to use updated PL/SQL logic. See Editioning.py

  • Support for Statement Caching. Reduce costs of frequently executed statements. Now available with all connections.

  • Support for setting application context during the creation of a connection. Make application metadata more accessible to the database, including in LOGON triggers. See AppContext.py

Other New Features

  • Continuous Query Notification use has been simplified. See DatabaseChangeNotification.py and QueryChangeNotification.py

  • Support for pickling/unpickling error objects

  • Support for binding native integers

  • Support setting the internal and external name for use in distributed transactions

  • Set the maximum lifetime of connections in a session pool

  • Larger row counts (greater than 2^32)

  • Increased default query array size to 100

Changes from cx_Oracle 5.2

In line with previous deprecations and announcements, the following items are no longer usable in cx_Oracle 5.3:

  • The variable attribute maxlength has been dropped. Use bufferSize instead.

  • The variable attribute allocelems has been dropped. Use numElements instead.

  • The types UNICODE, FIXED_UNICODE and LONG_UNICODE have been dropped. Use NCHAR, FIXED_NCHAR and LONG_NCHAR instead.

  • Callbacks on OCI functions are no longer supported.

Future Deprecation Announcements

In a future cx_Oracle 6 release, the following items will be removed:

  • The module, action and clientinfo arguments to connection creation are deprecated and will be removed in cx_Oracle 6. Use the new application context instead.

  • The cursor attribute numbersAsStrings is deprecated and will be removed in cx_Oracle 6. An output type handler should be used instead.

Things you could already do in cx_Oracle 5.2

All the new features in cx_Oracle 5.3 listed above are on top of a great history of database support. The high level features that you've already been using in the previous release are:

  • SQL and PL/SQL Execution

  • Extensive data type support

  • Fetching of large result sets


  • Binding PL/SQL Arrays

  • Large Objects: CLOBs and BLOBs

  • Transaction Management

  • Session Pooling

  • Database Resident Connection Pooling (DRCP)

  • Privileged Connections and Database startup/shutdown

  • External Authentication

  • Continuous Query Notification

  • Row Prefetching

  • Client Result Caching

  • End-to-end tracing

  • Oracle Database High Availability Features

A future cx_Oracle 6

I said you'd be impressed with cx_Oracle 5.3, but Anthony has already looked ahead to cx_Oracle 6, which aims to be even better. Over the past year, Anthony has been working hard on ODPI-C, an open source library of C code that simplifies and standardizes the use of common Oracle Call Interface (OCI) features, such as those used by cx_Oracle. ODPI-C was recently released on Github. As you can see from the cx_Oracle source code, the master branch of cx_Oracle code has been updated to use ODPI-C. If you want to test the current state of this future release, download a bundle from GitHub and build it. The release notes (so far) for user visible changes are here.


The move of cx_Oracle to under the umbrella of Oracle has given Anthony more time to focus on cx_Oracle and on making database access better for all developers.

Overall cx_Oracle is the most comprehensive and popular scripting language driver for Oracle Database. It takes advantage of the great features built into the Oracle client libraries and into Oracle Database. And, of course, Python cx_Oracle applications can take advantage of Oracle Net features such as network data encyption.

cx_Oracle 5.3 is a big release with support for some great Oracle Database features. Take a look.

cx_Oracle Resources

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Comments ( 2 )
  • Rafael Reuber Friday, March 10, 2017

    Awesome! It's really good to see that Oracle are contributing directly with cx_Oracle project. I'm pretty excited to see the next release!

  • fcbarclo Thursday, July 20, 2017
    cx_Oracle it's a great library.
    here https://github.com/fcbarclo/Otop my first application using cx_Oracle interface.
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