Appendix C: The python-oracledb and cx_Oracle Drivers

The python-oracledb driver is the renamed, major version successor to cx_Oracle 8.3. As a major release, the python-oracledb driver has :ref:`new features <releasenotes>` and some :ref:`deprecations`. Also see :ref:`upgrading83`.

Differences between the python-oracledb and cx_Oracle Drivers

The differences between the cx_Oracle 8.3 and python-oracledb drivers are listed here.

Mode differences from cx_Oracle

By default, python-oracledb runs in a 'Thin' mode which connects directly to Oracle Database. This mode does not need Oracle Client libraries. However, some :ref:`additional functionality <featuresummary>` is available when python-oracledb uses them. Python-oracledb is said to be in 'Thick' mode when Oracle Client libraries are used. See :ref:`enablingthick`. Both modes have comprehensive functionality supporting the Python Database API v2.0 Specification.

cx_Oracle always runs in a Thick mode using Oracle Client libraries. The features in python-oracledb Thick mode and cx_Oracle 8.3 are the same, subject to the :ref:`new features <releasenotes>`, some :ref:`deprecations <deprecations>`, and to other changes noted in this section.

Oracle Client Library Loading Differences from cx_Oracle

Oracle Client libraries are now only loaded if :func:`oracledb.init_oracle_client()` is called in your application. This changes python-oracledb to Thick mode. The init_oracle_client() method must be called before any :ref:`standalone connection <standaloneconnection>` or :ref:`connection pool <connpooling>` is created. If a connection or pool is created first in the default Thin mode, then Thick mode cannot be enabled.

See :ref:`enablingthick` for more information.

Calling the init_oracle_client() method immediately loads Oracle Client libraries. To emulate the cx_Oracle behavior of deferring library loading until the creation of the first connection (in the case when init_oracle_client() is not called), your application will need to explicitly defer calling init_oracle_client() as appropriate.

In python-oracledb, init_oracle_client() can now be called multiple times in the one Python process as long as its arguments are the same each time.

oracledb.clientversion()

The :func:`oracledb.clientversion()` method shows the version of the Oracle Client libraries being used. There is no Oracle Client used in the python-oracledb Thin mode so this function can only be called in python-oracledb Thick mode. If this function is called before :func:`oracledb.init_oracle_client()`, an exception is thrown.

Connection Differences from cx_Oracle

oracledb.connect() Differences

The :func:`oracledb.connect()` function in the python-oracledb driver differs from cx_Oracle:

Keyword parameters must be used in calls to :func:`oracledb.connect()`. This change makes the driver compliant with the Python Database API specification PEP 249. See :ref:`Standalone Connections <standaloneconnection>` and :ref:`connerrors`.
New optional keyword arguments can be passed to :func:`~oracledb.connect()`. For example you can pass the hostname, port and servicename as separate parameters instead of using an Easy Connect connection string. In python-oracledb Thin mode, some of the new arguments replace :ref:`sqlnet.ora <optnetfiles>` settings.
A new optional parameter params of type :ref:`ConnectParams <connparam>` can be used to encapsulate connection properties. See :ref:`usingconnparams` for more information.
The following parameters are desupported:
- encoding and nencoding: The encodings in use are always UTF-8.
- threaded: Threaded Oracle Call Interface (OCI) is now always enabled in Thick mode. This option is not relevant to the Thin mode.
See :ref:`deprecations` for more information.

The use of the class constructor method oracledb.Connection() to create connections is no longer recommended for creating connections. Use :func:`~oracledb.connect()` instead.

The :meth:`oracledb.makedsn()` method for creating the dsn value has been deprecated. New code should use :meth:`oracledb.ConnectParams()` or use the new keyword arguments in :func:`oracledb.connect()`.

Connection Object Differences

The :ref:`Connection object <connobj>` differences between the python-oracledb and cx_Oracle drivers are:

The attribute :attr:`Connection.maxBytesPerCharacter` is deprecated. This will return a constant value of 4 since encodings are always UTF-8.
A new boolean attribute, :attr:`Connection.thin` is available. This attribute is True if the connection was established in the Thin mode. In Thick mode, the value of this attribute is False.
The new method signature of :attr:`Connection.outputtypehandler` is handler(cursor, metadata). The old signature handler(cursor, name, default_type, length, precision, scale) was deprecated in python-oracledb 1.4 but will still work and will be removed in a future version.

See :ref:`connattrs` for more information.

Pooling Differences from cx_Oracle

It is recommended to use the new :ref:`ConnectionPool Object <connpool>` instead of the equivalent SessionPool object, which is deprecated. To create a connection pool, use :meth:`oracledb.create_pool()`, which is equivalent to calling cx_Oracle.SessionPool().

For more information, see :ref:`connpooling`.

oracledb.SessionPool() Differences

The python-oracledb oracledb.SessionPool() method (which is an alias of :func:`oracledb.create_pool()`) differs from cx_Oracle.SessionPool() as follows:

Keyword parameters must be used in calls. This change makes the driver compliant with the Python Database API specification PEP 249. See :ref:`Connection pooling <connpooling>` and :ref:`connerrors`.
Passing a value to the dsn parameter that contains the user name and password is now supported in the same way as :func:`oracledb.connect()`. For example dsn="un/pw@cs" can be used.
New optional keyword arguments can be passed to :func:`~oracledb.create_pool()`. For example you can pass the hostname, port and servicename as separate parameters instead of using an Easy Connect connection string. In python-oracledb Thin mode, some of the new arguments replace :ref:`sqlnet.ora <optnetfiles>` settings.
A new optional parameter params of type :ref:`PoolParams <poolparam>` can be used to encapsulate connection properties. See :ref:`usingconnparams` for more information.
The default mode is :data:`~oracledb.POOL_GETMODE_WAIT` instead of :data:`~oracledb.POOL_GETMODE_NOWAIT`. If the mode :data:`~oracledb.POOL_GETMODE_NOWAIT` is truly desired, modify any pool creation code to specify this value instead. Note the namespace of constants has been improved. Old names like SPOOL_ATTRVAL_NOWAIT can be used but are now deprecated.
The encoding and nenecoding parameters are deprecated and ignored. The encodings in use are always UTF-8.
New keyword arguments that are used internally to create a :ref:`PoolParams object <connparam>` before creating the connection.

SessionPool Object Differences

The SessionPool object (which is an alias for the :ref:`ConnectionPool object <connpool>`) differences between the python-oracledb and cx_Oracle drivers are:

A Python type() will show the class as oracledb.ConnectionPool instead of cx_Oracle.SessionPool.
A new boolean attribute, SessionPool.thin (see :attr:`ConnectionPool.thin`) is available. This attribute is True if the connection was established in the Thin mode. In Thick mode, the value of this attribute is False.

Cursor Object Differences from cx_Oracle

The differences between the :ref:`Cursor object <cursorobj>` in python-oracledb and cx_Oracle drivers are:

:meth:`Cursor.fetchmany()`: The name of the size argument of fetchmany() is size. This change was done to comply with PEP 249. The previous keyword argument name, numRows is deprecated.
Cursor.fetchraw(): This method was previously deprecated in cx_Oracle 8.2 and has been removed in python-oracledb. Instead, use one of the other fetch methods such as :meth:`Cursor.fetchmany()`.
Cursor.executemanyprepared(): This method was previously deprecated in cx_Oracle 6.4 and has been removed in python-oracledb. Instead, use :meth:`Cursor.executemany()`, by passing None for the statement argument and an integer for the parameters argument.
Cursor.bindarraysize: This attribute is desupported and removed in python-oracledb. It is not needed in the application code.
:attr:`Cursor.rowcount`: After :meth:`Cursor.execute()` or :meth:`Cursor.executemany()` with PL/SQL statements, Cursor.rowcount will return 0. If the cursor or connection are not open, then the value -1 will be returned as required by the Python Database API.
:attr:`Cursor.description`: This attribute was previously a sequence of 7-item sequences in cx_Oracle and python-oracledb. Each of these sequences contained information describing one result column, that is, (name, type, display_size, internal_size, precision, scale, null_ok). In python-oracledb 1.4, this attribute was changed to a sequence of :ref:`FetchInfo <fetchinfoobj>` objects. Each FetchInfo object describes one result column and can behave as a 7-tuple like before, but contains additional information that may be helpful when using :ref:`output type handlers <outputtypehandlers>`.
:attr:`Cursor.outputtypehandler`: The new method signature of this attribute is handler(cursor, metadata). The old signature handler(cursor, name, default_type, length, precision, scale) was deprecated in python-oracledb 1.4 but will still work and will be removed in a future version.

Fetching IS JSON Column Differences from cx_Oracle

In python-oracledb, VARCHAR2 and LOB columns that have the IS JSON constraint enabled are fetched as Python objects. These columns are fetched in the same way that :ref:`JSON type columns <json21fetch>` are fetched when using Oracle Database 21c (or later). The returned value varies depending on the JSON data. If the JSON data is an object, then a dictionary is returned. If it is an array, then a list is returned. If it is a scalar value, then that particular scalar value is returned.

In cx_Oracle, VARCHAR2 and LOB columns that have the IS JSON constraint enabled are fetched as strings and LOB objects respectively. To enable this same fetch behavior in python-oracledb, you must use an :ref:`output type handler <outputtypehandlers>` as shown below.

def type_handler(cursor, fetch_info):
    if fetch_info.is_json:
        return cursor.var(fetch_info.type_code, cursor.arraysize)

Advanced Queuing (AQ) Differences from cx_Oracle

Use the new :ref:`Advanced Queuing (AQ) <aqusermanual>` API instead of the older API which was deprecated in cx_Oracle 7.2 and is not available in python-oracledb. Note that AQ is only available in python-oracledb Thick mode.

Replace:

Connection.deq() with :meth:`Queue.deqone()` or :meth:`Queue.deqmany()`
Connection.deqoptions() with attribute :attr:`Queue.deqoptions`
Connection.enq() with :meth:`Queue.enqone()` or :meth:`Queue.enqmany()`
Connection.enqoptions() with attribute :attr:`Queue.enqoptions`

The AQ support in python-oracledb has the following enhancements from cx_Oracle:

AQ messages can be enqueued and dequeued as a JSON payload type
Recipient lists can be enqueued and dequeued
Enqueue options, dequeue options, and message properties can be set

See :ref:`Oracle Advanced Queuing (AQ) <aqusermanual>`.

Error Handling Differences from cx_Oracle

In python-oracledb Thick mode, error messages generated by the Oracle Client libraries and the ODPI-C layer used by cx_Oracle and python-oracledb in Thick mode are mostly returned unchanged from cx_Oracle 8.3. Some exceptions shown below.

Note that the python-oracledb driver error messages can also vary between Thin and Thick modes. See :ref:`errorhandling`.

ConnectionPool.acquire() Message Differences

:meth:`ConnectionPool.acquire()` ORA errors will be mapped to DPY errors. For example:

DPY-4005: timed out waiting for the connection pool to return a connection

replaces the cx_Oracle 8.3 error:

ORA-24459: OCISessionGet() timed out waiting for pool to create new connections

Dead Connection Detection and Timeout Message Differences

Application code which detects connection failures or statement execution timeouts will need to check for new errors, DPY-4011 and DPY-4024 respectively. The error DPY-1001 is returned if an already dead connection is attempted to be used.

The new Error object attribute :attr:`~oracledb._Error.full_code` may be useful for checking the error code.

Example error messages are:

Scenario 1: An already closed or dead connection was attempted to be used.

python-oracledb Thin Error:
```
DPY-1001: not connected to database
```
python-oracledb Thick Error:
```
DPY-1001: not connected to database
```
cx_Oracle Error:
```
not connected
```

Scenario 2: The database side of the connection was terminated while the connection was being used.

python-oracledb Thin Error:

DPY-4011: the database or network closed the connection

python-oracledb Thick Error:

DPY-4011: the database or network closed the connection
DPI-1080: connection was closed by ORA-%d

cx_Oracle Error:

DPI-1080: connection was closed by ORA-%d

Scenario 3: Statement execution exceeded the :attr:`connection.call_timeout` value.

python-oracledb Thin Error:

DPY-4024: call timeout of {timeout} ms exceeded

python-oracledb Thick Error:

DPY-4024: call timeout of {timeout} ms exceeded
DPI-1067: call timeout of %u ms exceeded with ORA-%d

cx_Oracle Error:

DPI-1067: call timeout of %u ms exceeded with ORA-%d

Upgrading from cx_Oracle 8.3 to python-oracledb

This section provides the detailed steps needed to upgrade from cx_Oracle 8.3 to python-oracledb.

Things to Know Before the Upgrade

Below is a list of some useful things to know before upgrading from cx_Oracle to python-oracledb:

You can have both cx_Oracle and python-oracledb installed, and can use both in the same application.
If you only want to use the python-oracledb driver in Thin mode, then you do not need Oracle Client libraries such as from Oracle Instant Client. You only need to :ref:`install <installation>` the driver itself:
```
python -m pip install oracledb
```
See :ref:`driverdiff`.
The python-oracledb Thin and Thick modes have the same level of support for the Python Database API specification and can be used to connect to on-premises databases and Oracle Cloud databases. However, the python-oracledb Thin mode does not support some of the advanced Oracle Database features such as Application Continuity (AC), Advanced Queuing (AQ), Continuous Query Notification (CQN), and Sharding. See :ref:`Features Supported <featuresummary>` for details.
python-oracledb can be used in SQLAlchemy, Django, Pandas, Superset and other frameworks and Object-relational Mappers (ORMs). To use python-oracledb in versions of these libraries that don't have native support for the new name, you can override the use of cx_Oracle with a few lines of code. See :ref:`frameworks`.
python-oracledb connection and pool creation calls require keyword arguments to conform with the Python Database API specification. For example you must use:
```
oracledb.connect(user="scott", password=pw, dsn="localhost/orclpdb")
```
This no longer works:
```
oracledb.connect("scott", pw, "localhost/orclpdb")
```
The python-oracledb Thin mode ignores all NLS environment variables. It also ignores the ORA_TZFILE environment variable. Thick mode does use these variables. See :ref:`globalization` for alternatives.
To use a tnsnames.ora file in the python-oracledb Thin mode, you must explicitly set the environment variable TNS_ADMIN to the directory containing the file, or set :attr:`defaults.config_dir`, or set the config_dir parameter when connecting.

Only python-oracledb Thick mode will read :ref:`sqlnet.ora <optnetfiles>` files. The Thin mode lets equivalent properties be set in the application when connecting.

Configuration files in a "default" location such as the Instant Client network/admin/ subdirectory, in $ORACLE_HOME/network/admin/, or in $ORACLE_BASE/homes/XYZ/network/admin/ (in a read-only Oracle Database home) are not automatically loaded in Thin mode. Default locations are only automatically searched in Thick mode.
To use the python-oracledb Thin mode in an ORACLE_HOME database installation environment, you must use an explicit connection string since the ORACLE_SID, TWO_TASK, and LOCAL environment variables are not used. They are used in Thick mode.
This is a major release so some previously deprecated features are no longer available. See :ref:`deprecations`.

Steps to Upgrade to python-oracledb

If you are creating new applications, follow :ref:`installation` and refer to other sections of the documentation for usage information.

To upgrade existing code from cx_Oracle to python-oracledb, perform the following steps:

Install the new python-oracledb module:
```
python -m pip install oracledb
```
See :ref:`installation` for more details.
Import the new interface module. This can be done in two ways. You can change:
```
import cx_Oracle
```
to:
```
import oracledb as cx_Oracle
```
Alternatively, you can replace all references to the module cx_Oracle with oracledb. For example, change:
```
import cx_Oracle
c = cx_Oracle.connect(...)
```
to:
```
import oracledb
c = oracledb.connect(...)
```
Any new code being introduced during the upgrade should aim to use the latter syntax.
Use keyword parameters in calls to :func:`oracledb.connect()`, oracledb.Connection(), and oracledb.SessionPool().

You must replace positional parameters with keyword parameters, unless only one parameter is being passed. Python-oracledb uses keyword parameters exclusively unless a DSN containing the user, password, and connect string combined, for example un/pw@cs, is used. This change makes the driver compliant with the Python Database API specification PEP 249.

For example, the following code will fail:
```
c = oracledb.connect("un", "pw", "cs")
```
and needs to be changed to:
```
c = oracledb.connect(user="un", password="pw", dsn="cs")
```
The following example will continue to work without change:
```
c = oracledb.connect("un/pw@cs")
```
Review obsolete encoding parameters in calls to :func:`oracledb.connect()`, oracledb.Connection(), and oracledb.SessionPool():
- encoding and nencoding are desupported in python-oracledb and must be removed. The python-oracledb driver uses UTF-8 exclusively.
- threaded is desupported in :func:`oracledb.connect()` and oracledb.Connection() by python-oracledb and must be removed. This parameter was already ignored in oracledb.SessionPool() from cx_Oracle 8.2.
Remove all references to :meth:`Cursor.fetchraw()` as this method was deprecated in cx_Oracle 8.2 and has been removed in python-oracledb. Instead, use one of the other fetch methods such as :meth:`Cursor.fetchmany()`.
The default value of the oracledb.SessionPool() parameter :attr:`~Connection.getmode` now waits for an available connection. That is, the default is now :data:`~oracledb.POOL_GETMODE_WAIT` instead of :data:`~oracledb.POOL_GETMODE_NOWAIT`. The new default value improves the behavior for most applications. If the pool is in the middle of growing, the new value prevents transient connection creation errors from occurring when using the Thin mode, or when using the Thick mode with recent Oracle Client libraries.

If the old default value is required, modify any pool creation code to explicitly specify getmode=oracledb.POOL_GETMODE_NOWAIT.

Note a :ref:`ConnectionPool class <connpool>` deprecates the equivalent SessionPool class. The method :meth:`oracledb.create_pool()` deprecates the use of oracledb.SessionPool(). New pool parameter constant names such as :data:`~oracledb.POOL_GETMODE_NOWAIT` and :data:`~oracledb.PURITY_SELF` are now preferred. The old namespaces still work.
The method signature of the :ref:`output type handler <outputtypehandlers>` which can be specified on a :attr:`connection <Connection.outputtypehandler>` or on a :attr:`cursor <Cursor.outputtypehandler>` is handler(cursor, metadata). The old signature handler(cursor, name, default_type, length, precision, scale) was deprecated in python-oracledb 1.4 but will still work and will be removed in a future version.
VARCHAR2 and LOB columns that have the IS JSON constraint enabled are fetched by default as Python objects in python-oracledb. In cx_Oracle, VARCHAR2 and LOB columns that contain JSON data are fetched by default as strings and LOB objects respectively. See :ref:`fetchisjson`.
Review the following sections to see if your application requirements are satisfied by the python-oracledb Thin mode:
- :ref:`featuresummary`
- :ref:`driverdiff`
If your application requirements are not supported by the Thin mode, then use the python-oracledb Thick mode.
Review :ref:`compatibility`.

If your code base uses an older cx_Oracle version, review the previous :ref:`release notes <releasenotes>` for additional changes to modernize the code.

Modernize code as needed or desired. See :ref:`deprecations` for the list of deprecations in python-oracledb.

Additional Upgrade Steps to use python-oracledb Thin Mode

To use python-oracledb Thin mode, the following changes need to be made in addition to the common :ref:`commonupgrade`:

Remove calls to :func:`~oracledb.init_oracle_client` since this turns on the python-oracledb Thick mode.
If the config_dir parameter of :func:`~oracledb.init_oracle_client` had been used, then set the new :attr:`defaults.config_dir` attribute to the desired value or set the config_dir parameter when connecting. For example:
```
oracledb.defaults.config_dir = "/opt/oracle/config"
```
Also, see :ref:`sqlnetclientconfig`.
If the driver_name parameter of :func:`~oracledb.init_oracle_client` had been used, then set the new :attr:`defaults.driver_name` attribute to the desired value or set the driver_name parameter when connecting. The convention for this parameter is to separate the product name from the product version by a colon and single blank characters. For example:
```
oracledb.defaults.driver_name = "python-oracledb : 1.2.0"
```
See :ref:`otherinit`.
If the application is connecting using a :ref:`TNS Alias <netservice>` from a tnsnames.ora file located in a "default" location such as the Instant Client network/admin/ subdirectory, in $ORACLE_HOME/network/admin/, or in $ORACLE_BASE/homes/XYZ/network/admin/ (in a read-only Oracle Database home), then the configuration file directory must now explicitly be set as shown in Step 2.
Remove calls to :func:`oracledb.clientversion()` which is only available in the python-oracledb Thick mode. Oracle Client libraries are not available in Thin mode.
Ensure that any assumptions about when connections are created in the connection pool are eliminated. The python-oracledb Thin mode creates connections in a daemon thread and so the attribute :attr:`ConnectionPool.opened` will change over time and will not be equal to :attr:`ConnectionPool.min` immediately after the pool is created. Note that this behavior is also similar in recent versions of the Oracle Call Interface (OCI) Session Pool used by the Thick mode. Unless the oracledb.SessionPool() function's parameter getmode is :data:`oracledb.POOL_GETMODE_WAIT`, then applications should not call :meth:`ConnectionPool.acquire()` until sufficient time has passed for connections in the pool to be created.
Review error handling improvements. See :ref:`errorhandling`.
Review locale and globalization usage. See :ref:`globalization`.

Additional Upgrade Steps to use python-oracledb Thick Mode

To use python-oracledb Thick mode, the following changes need to be made in addition to the common :ref:`commonupgrade`:

The function :func:`oracledb.init_oracle_client()` must be called. It can be called anywhere before the first call to :func:`~oracledb.connect()`, oracledb.Connection(), and oracledb.SessionPool(). This enables the Thick mode. See :ref:`enablingthick` for more details.

The requirement to call init_oracle_client() means that Oracle Client library loading is not automatically deferred until the driver is first used, such as when a connection is opened. The application must explicitly manage this, if deferral is required. In python-oracledb, init_oracle_client() can be called multiple times in a Python process as long as arguments are the same.

Note that on Linux and related operating systems, the init_oracle_client() parameter lib_dir should not be passed. Instead, set the system library search path with ldconfig or LD_LIBRARY_PATH prior to running Python.
Replace all usages of the deprecated Advanced Queuing API with the new API originally introduced in cx_Oracle 7.2, see :ref:`aqusermanual`.
Review error handling improvements. See :ref:`errorhandling`.

Code to Aid the Upgrade to python-oracledb

Toggling between Drivers

The sample oracledb_upgrade.py shows a way to toggle applications between cx_Oracle and the two python-oracledb modes. Note this script cannot map some functionality such as :ref:`obsolete cx_Oracle <compatibility>` features or error message changes.

An example application showing this module in use is:

# test.py

import oracledb_upgrade as cx_Oracle
import os

un = os.environ.get("PYTHON_USERNAME")
pw = os.environ.get("PYTHON_PASSWORD")
cs = os.environ.get("PYTHON_CONNECTSTRING")

connection = cx_Oracle.connect(user=un, password=pw, dsn=cs)
with connection.cursor() as cursor:
    sql = """SELECT UNIQUE CLIENT_DRIVER
             FROM V$SESSION_CONNECT_INFO
             WHERE SID = SYS_CONTEXT('USERENV', 'SID')"""
    for r, in cursor.execute(sql):
        print(r)

You can then choose what mode is in use by setting the environment variable ORA_PYTHON_DRIVER_TYPE to one of "cx", "thin", or "thick":

export ORA_PYTHON_DRIVER_TYPE=thin
python test.py

Output shows the python-oracledb Thin mode was used:

python-oracledb thn : 1.0.0

You can customize oracledb_upgrade.py to your needs. For example, if your connection and pool creation calls always use keyword parameters, you can remove the shims that map from positional arguments to keyword arguments.

The simplest form is shown in :ref:`frameworks`.

Testing Which Driver is in Use

To know whether the driver is cx_Oracle or python-oracledb, you can use code similar to:

import oracledb as cx_Oracle
# or:
# import cx_Oracle

if cx_Oracle.__name__ == 'cx_Oracle':
       print('cx_Oracle')
else:
       print('oracledb')

Another method that can be used to check which driver is in use is to query V$SESSION_CONNECT_INFO, see :ref:`vsessconinfo`.

Python Frameworks, SQL Generators, and ORMs

Python-oracledb's Thin and :ref:`Thick <enablingthick>` modes cover the feature needs of frameworks that depend upon the Python Database API.

For versions of SQLAlchemy, Django, Superset, other frameworks, object-relational mappers (ORMs), and libraries that do not have native support for python-oracledb, you can add code like this to use python-oracledb instead of cx_Oracle:

import sys
import oracledb
oracledb.version = "8.3.0"
sys.modules["cx_Oracle"] = oracledb

Note

This must occur before any import of cx_Oracle by your code or the library.

To use Thick mode, for example if you need to connect to Oracle Database 11gR2, also add a call to :meth:`oracledb.init_oracle_client()` with the appropriate parameters for your environment, see :ref:`enablingthick`.

SQLAlchemy 2 and Django 5 have native support for python-oracledb so this code snippet is not needed in those versions.

Connecting with SQLAlchemy

SQLAlchemy 1.4

# Using python-oracledb in SQLAlchemy 1.4

import os
import getpass
import oracledb
from sqlalchemy import create_engine
from sqlalchemy import text

import sys
oracledb.version = "8.3.0"
sys.modules["cx_Oracle"] = oracledb

# Uncomment to use python-oracledb Thick mode
# Review the doc for the appropriate parameters
#oracledb.init_oracle_client(<your parameters>)

un = os.environ.get("PYTHON_USERNAME")
cs = os.environ.get("PYTHON_CONNECTSTRING")
pw = getpass.getpass(f'Enter password for {un}@{cs}: ')

# Note the first argument is different for SQLAlchemy 1.4 and 2
engine = create_engine(f'oracle://@',
                       connect_args={
                           "user": un,
                           "password": pw,
                           "dsn": cs
                       }
         )

with engine.connect() as connection:
    print(connection.scalar(text(
           """SELECT UNIQUE CLIENT_DRIVER
              FROM V$SESSION_CONNECT_INFO
              WHERE SID = SYS_CONTEXT('USERENV', 'SID')""")))

Note that the create_engine() argument driver declaration uses oracle:// for SQLAlchemy 1.4 and oracle+oracledb:// for SQLAlchemy 2.

The connect_args dictionary can use any appropriate :meth:`oracledb.connect()` parameter.

SQLAlchemy 2

# Using python-oracledb in SQLAlchemy 2

import os
import getpass
import oracledb
from sqlalchemy import create_engine
from sqlalchemy import text

# Uncomment to use python-oracledb Thick mode
# Review the doc for the appropriate parameters
#oracledb.init_oracle_client(<your parameters>)

un = os.environ.get("PYTHON_USERNAME")
cs = os.environ.get("PYTHON_CONNECTSTRING")
pw = getpass.getpass(f'Enter password for {un}@{cs}: ')

# Note the first argument is different for SQLAlchemy 1.4 and 2
engine = create_engine(f'oracle+oracledb://@',
                       connect_args={
                           "user": un,
                           "password": pw,
                           "dsn": cs
                       }
         )

with engine.connect() as connection:
    print(connection.scalar(text(
           """SELECT UNIQUE CLIENT_DRIVER
              FROM V$SESSION_CONNECT_INFO
              WHERE SID = SYS_CONTEXT('USERENV', 'SID')""")))

Note that the create_engine() argument driver declaration uses oracle:// for SQLAlchemy 1.4 and oracle+oracledb:// for SQLAlchemy 2.

The connect_args dictionary can use any appropriate :meth:`oracledb.connect()` parameter.

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appendix_c.rst

appendix_c.rst

Appendix C: The python-oracledb and cx_Oracle Drivers

Differences between the python-oracledb and cx_Oracle Drivers

Mode differences from cx_Oracle

Oracle Client Library Loading Differences from cx_Oracle

oracledb.clientversion()

Connection Differences from cx_Oracle

oracledb.connect() Differences

Connection Object Differences

Pooling Differences from cx_Oracle

oracledb.SessionPool() Differences

SessionPool Object Differences

Cursor Object Differences from cx_Oracle

Fetching IS JSON Column Differences from cx_Oracle

Advanced Queuing (AQ) Differences from cx_Oracle

Error Handling Differences from cx_Oracle

ConnectionPool.acquire() Message Differences

Dead Connection Detection and Timeout Message Differences

Upgrading from cx_Oracle 8.3 to python-oracledb

Things to Know Before the Upgrade

Steps to Upgrade to python-oracledb

Additional Upgrade Steps to use python-oracledb Thin Mode

Additional Upgrade Steps to use python-oracledb Thick Mode

Code to Aid the Upgrade to python-oracledb

Toggling between Drivers

Testing Which Driver is in Use

Python Frameworks, SQL Generators, and ORMs

Connecting with SQLAlchemy

Files

appendix_c.rst

Latest commit

History

appendix_c.rst

File metadata and controls

Appendix C: The python-oracledb and cx_Oracle Drivers

Differences between the python-oracledb and cx_Oracle Drivers

Mode differences from cx_Oracle

Oracle Client Library Loading Differences from cx_Oracle

oracledb.clientversion()

Connection Differences from cx_Oracle

oracledb.connect() Differences

Connection Object Differences

Pooling Differences from cx_Oracle

oracledb.SessionPool() Differences

SessionPool Object Differences

Cursor Object Differences from cx_Oracle

Fetching IS JSON Column Differences from cx_Oracle

Advanced Queuing (AQ) Differences from cx_Oracle

Error Handling Differences from cx_Oracle

ConnectionPool.acquire() Message Differences

Dead Connection Detection and Timeout Message Differences

Upgrading from cx_Oracle 8.3 to python-oracledb

Things to Know Before the Upgrade

Steps to Upgrade to python-oracledb

Additional Upgrade Steps to use python-oracledb Thin Mode

Additional Upgrade Steps to use python-oracledb Thick Mode

Code to Aid the Upgrade to python-oracledb

Toggling between Drivers

Testing Which Driver is in Use

Python Frameworks, SQL Generators, and ORMs

Connecting with SQLAlchemy