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python-cx_Oracle/doc/src/api_manual/module.rst
Anthony Tuininga b04f538467 Documentation improvements.
2020-07-02 19:54:47 -06:00

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.. module:: cx_Oracle
.. _module:
****************
Module Interface
****************
.. data:: __future__
Special object which contains attributes which control the behavior of
cx_Oracle, allowing for opting in for new features. No attributes are
currently supported so all attributes will silently ignore being set and
will always appear to have the value None.
.. note::
This method is an extension to the DB API definition.
.. versionadded:: 6.2
.. function:: Binary(string)
Construct an object holding a binary (long) string value.
.. function:: clientversion()
Return the version of the client library being used as a 5-tuple. The five
values are the major version, minor version, update number, patch number
and port update number.
.. note::
This method is an extension to the DB API definition.
.. function:: connect(user=None, password=None, dsn=None, \
mode=cx_Oracle.DEFAULT_AUTH, handle=0, pool=None, threaded=False, \
events=False, cclass=None, purity=cx_Oracle.ATTR_PURITY_DEFAULT, \
newpassword=None, encoding=None, nencoding=None, edition=None, \
appcontext=[], tag=None, matchanytag=None, shardingkey=[], \
supershardingkey=[])
Connection(user=None, password=None, dsn=None, \
mode=cx_Oracle.DEFAULT_AUTH, handle=0, pool=None, threaded=False, \
events=False, cclass=None, purity=cx_Oracle.ATTR_PURITY_DEFAULT, \
newpassword=None, encoding=None, nencoding=None, edition=None, \
appcontext=[], tag=None, matchanytag=False, shardingkey=[], \
supershardingkey=[])
Constructor for creating a connection to the database. Return a
:ref:`connection object <connobj>`. All parameters are optional and can be
specified as keyword parameters. See :ref:`connhandling` information about
connections.
The dsn (data source name) is the TNS entry (from the Oracle names server
or tnsnames.ora file) or is a string like the one returned from
:meth:`~cx_Oracle.makedsn()`. If the user parameter is passed and the
password and dsn parameters are not passed, the user parameter is assumed
to be a connect string in the format ``user/password@dsn``, the same format
accepted by Oracle applications such as SQL\*Plus. See :ref:`connstr` for
more information.
If the mode is specified, it must be one of the
:ref:`connection authorization modes<connection-authorization-modes>`
which are defined at the module level.
If the handle is specified, it must be of type OCISvcCtx\* and is only of
use when embedding Python in an application (like PowerBuilder) which has
already made the connection.
The pool parameter is expected to be a
:ref:`session pool object <sesspool>` and the use of this parameter is the
equivalent of calling :meth:`SessionPool.acquire()`. Parameters not
accepted by that method are ignored.
The threaded parameter is expected to be a boolean expression which
indicates whether or not Oracle should wrap accesses to connections with a
mutex. Doing so in single threaded applications imposes a performance
penalty of about 10-15% which is why the default is False.
The events parameter is expected to be a boolean expression which indicates
whether or not to initialize Oracle in events mode. This is required for
continuous query notification and high availability event notifications.
The cclass parameter is expected to be a string and defines the connection
class for database resident connection pooling (DRCP).
The purity parameter is expected to be one of
:data:`~cx_Oracle.ATTR_PURITY_NEW`, :data:`~cx_Oracle.ATTR_PURITY_SELF`, or
:data:`~cx_Oracle.ATTR_PURITY_DEFAULT`.
The newpassword parameter is expected to be a string if specified and sets
the password for the logon during the connection process.
See the :ref:`globalization <globalization>` section for details on the
encoding and nencoding parameters. Note the default encoding and nencoding
values changed to "UTF-8" in cx_Oracle 8, and any character set in NLS_LANG
is ignored.
The edition parameter is expected to be a string if specified and sets the
edition to use for the session. It is only relevant if both the client and
the database are at least Oracle Database 11.2. If this parameter is used
with the cclass parameter the exception "DPI-1058: edition not supported
with connection class" will be raised.
The appcontext parameter is expected to be a list of 3-tuples, if specified,
and sets the application context for the connection. Application context
is available in the database by using the sys_context() PL/SQL method and
can be used within a logon trigger as well as any other PL/SQL procedures.
Each entry in the list is expected to contain three strings: the namespace,
the name and the value.
The tag parameter, if specified, is expected to be a string and will limit
the sessions that can be returned from a session pool unless the
matchanytag parameter is set to True. In that case sessions with the
specified tag will be preferred over others, but if no such sessions are
available a session with a different tag may be returned instead. In any
case, untagged sessions will always be returned if no sessions with the
specified tag are available. Sessions are tagged when they are
:meth:`released <SessionPool.release>` back to the pool.
The shardingkey and supershardingkey parameters, if specified, are expected
to be a sequence of values which will be used to identify the database
shard to connect to. The key values can be strings, numbers, bytes or dates.
.. function:: Cursor(connection)
Constructor for creating a cursor. Return a new
:ref:`cursor object <cursorobj>` using the connection.
.. note::
This method is an extension to the DB API definition.
.. function:: Date(year, month, day)
Construct an object holding a date value.
.. function:: DateFromTicks(ticks)
Construct an object holding a date value from the given ticks value (number
of seconds since the epoch; see the documentation of the standard Python
time module for details).
.. function:: init_oracle_client(lib_dir=None, config_dir=None, \
error_url=None, driver_name=None)
Initialize the Oracle client library now, rather than when
:func:`cx_Oracle.clientversion()`, :func:`cx_Oracle.connect()` or
:func:`cx_Oracle.SessionPool()` is called for the first time. If
initialization has already taken place, an exception is raised.
If the parameter `lib_dir` is not `None` or the empty string,
the specified directory is the only one searched for the Oracle Client
libraries; otherwise, the standard way of locating the Oracle Client
library is used.
If the parameter `config_dir` is not `None` or the empty string, the
specified directory is used to find Oracle Client library configuration
files. This is equivalent to setting the environment variable `TNS_ADMIN`
and overrides any value already set in `TNS_ADMIN`. If this parameter is not
set, the standard way of locating Oracle Client library configuration files
is used.
If the parameter `error_url` is not `None` or the empty string, the
specified value is included in the message of the exception raised when the
Oracle Client library cannot be loaded; otherwise, the :ref:`installation`
URL is included.
If the parameter `driver_name` is not `None` or the empty string, the
specified value can be found in database views that give information about
connections. For example, it is in the ``CLIENT_DRIVER`` column of
``V$SESSION_CONNECT_INFO``. The standard is to set this value to
``"<name> : version>"``, where <name> is the name of the driver and
<version> is its version. Theere should be a single space character before
and after the colon. If this value is not specified, then the default
value of "cx_Oracle : <version>" is used.
See :ref:`initialization` for more discussion.
.. note::
This method is an extension to the DB API definition.
.. function:: makedsn(host, port, sid=None, service_name=None, region=None, \
sharding_key=None, super_sharding_key=None)
Return a string suitable for use as the dsn parameter for
:meth:`~cx_Oracle.connect()`. This string is identical to the strings that
are defined by the Oracle names server or defined in the tnsnames.ora file.
.. note::
This method is an extension to the DB API definition.
.. function:: SessionPool(user=None, password=None, dsn=None, min=1, max=2, \
increment=1, connectiontype=cx_Oracle.Connection, threaded=False, \
getmode=cx_Oracle.SPOOL_ATTRVAL_NOWAIT, events=False, \
homogeneous=True, externalauth=False, encoding=None, nencoding=None, \
edition=None, timeout=0, waitTimeout=0, maxLifetimeSession=0, \
sessionCallback=None, maxSessionsPerShard=0)
Create and return a :ref:`session pool object <sesspool>`. Session pooling
(also known as connection pooling) creates a pool of available connections
to the database, allowing applications to acquire a connection very quickly.
It is of primary use in a server where connections are requested in rapid
succession and used for a short period of time, for example in a web server.
See :ref:`connpool` for more information.
Connection pooling in cx_Oracle is handled by Oracle's
`Session pooling <https://www.oracle.com/pls/topic/lookup?
ctx=dblatest&id=GUID-F9662FFB-EAEF-495C-96FC-49C6D1D9625C>`__
technology. This allows cx_Oracle applications to support features
like `Application Continuity <https://www.oracle.com/pls/topic/lookup?
ctx=dblatest&id=GUID-A8DD9422-2F82-42A9-9555-134296416E8F>`__.
The user, password and dsn parameters are the same as for
:meth:`cx_Oracle.connect()`
The min, max and increment parameters control pool growth behavior. A fixed
pool size where min equals max is recommended to help prevent connection
storms and to help overall system stability. The min parameter is the
number of connections opened when the pool is created. The increment is the
number of connections that are opened whenever a connection request exceeds
the number of currently open connections. The max parameter is the maximum
number of connections that can be open in the connection pool.
Note that when using :ref:`external authentication <extauth>`,
:ref:`heterogeneous pools <connpooltypes>`, or :ref:`drcp`, then the pool
growth behavior is different. In these cases the number of connections
created at pool startup is always zero, and the increment is always one.
If the connectiontype parameter is specified, all calls to
:meth:`~SessionPool.acquire()` will create connection objects of that type,
rather than the base type defined at the module level.
The threaded parameter is expected to be a boolean expression which
indicates whether Oracle should wrap accesses to connections with a mutex.
Doing so in single threaded applications imposes a performance penalty of
about 10-15% which is why the default is False.
The getmode parameter indicates whether or not future
:func:`SessionPool.acquire()` calls will wait for available connections. It
can be one of the :ref:`Session Pool Get Modes <sesspoolmodes>` values.
The events parameter is expected to be a boolean expression which indicates
whether or not to initialize Oracle in events mode. This is required for
continuous query notification and high availability event notifications.
The homogeneous parameter is expected to be a boolean expression which
indicates whether or not to create a homogeneous pool. A homogeneous pool
requires that all connections in the pool use the same credentials. As such
proxy authentication and external authentication is not possible with a
homogeneous pool. See :ref:`Heterogeneous and Homogeneous Connection Pools
<connpooltypes>`.
The externalauth parameter is expected to be a boolean expression which
indicates whether or not external authentication should be used. External
authentication implies that something other than the database is
authenticating the user to the database. This includes the use of operating
system authentication and Oracle wallets. See :ref:`Connecting Using
External Authentication <extauth>`.
The encoding and nencoding parameters set the encodings used for string
values transferred between cx_Oracle and Oracle Database, see
:ref:`Character Sets and Globalization <globalization>`. Note the default
encoding and nencoding values changed to "UTF-8" in cx_Oracle 8, and any
character set in NLS_LANG is ignored.
The edition parameter is expected to be a string, if specified, and sets the
edition to use for the sessions in the pool. It is only relevant if both the
client and the server are at least Oracle Database 11.2. See
:ref:`Edition-Based Redefinition (EBR) <ebr>`.
The timeout parameter is expected to be an integer, if specified, and sets
the length of time (in seconds) after which idle sessions in the pool are
terminated. Note that termination only occurs when the pool is accessed.
The default value of 0 means that no idle sessions are terminated.
The waitTimeout parameter is expected to be an integer, if specified, and
sets the length of time (in milliseconds) that the caller should wait for
a session to become available in the pool before returning with an error.
This value is only used if the getmode parameter is set to the value
:data:`cx_Oracle.SPOOL_ATTRVAL_TIMEDWAIT`.
The maxLifetimeSession parameter is expected to be an integer, if
specified, and sets the maximum length of time (in seconds) a pooled
session may exist. Sessions that are in use will not be closed. They become
candidates for termination only when they are released back to the pool and
have existed for longer than maxLifetimeSession seconds. Note that
termination only occurs when the pool is accessed. The default value is 0
which means that there is no maximum length of time that a pooled session
may exist.
The sessionCallback parameter is expected to be either a string or a
callable. If the sessionCallback parameter is a callable, it will be called
when a newly created connection is returned from the pool, or when a tag is
requested and that tag does not match the connection's actual tag. The
callable will be invoked with the connection and the requested tag as its
only parameters. If the parameter is a string, it should be the name of a
PL/SQL procedure that will be called when :func:`SessionPool.acquire()`
requests a tag and that tag does not match the connection's actual tag. See
:ref:`Session CallBacks for Setting Pooled Connection State
<sessioncallback>`. Support for the PL/SQL procedure requires Oracle Client
libraries 12.2 or later. See the `OCI documentation
<https://www.oracle.com/pls/topic/lookup?ctx=dblatest&
id=GUID-B853A020-752F-494A-8D88-D0396EF57177>`__ for more information.
The maxSessionsPerShard parameter is expected to be an integer, if
specified, and sets the maximum number of sessions in the pool that can be
used for any given shard in a sharded database. This value is ignored if
the Oracle client library version is less than 18.3.
.. note::
This method is an extension to the DB API definition.
.. function:: Time(hour, minute, second)
Construct an object holding a time value.
.. note::
The time only data type is not supported by Oracle. Calling this
function will raise a NotSupportedError exception.
.. function:: TimeFromTicks(ticks)
Construct an object holding a time value from the given ticks value (number
of seconds since the epoch; see the documentation of the standard Python
time module for details).
.. note::
The time only data type is not supported by Oracle. Calling this
function will raise a NotSupportedError exception.
.. function:: Timestamp(year, month, day, hour, minute, second)
Construct an object holding a time stamp value.
.. function:: TimestampFromTicks(ticks)
Construct an object holding a time stamp value from the given ticks value
(number of seconds since the epoch; see the documentation of the standard
Python time module for details).
.. _constants:
Constants
=========
General
-------
.. data:: apilevel
String constant stating the supported DB API level. Currently '2.0'.
.. data:: buildtime
String constant stating the time when the binary was built.
.. note::
This constant is an extension to the DB API definition.
.. data:: paramstyle
String constant stating the type of parameter marker formatting expected by
the interface. Currently 'named' as in 'where name = :name'.
.. data:: threadsafety
Integer constant stating the level of thread safety that the interface
supports. Currently 2, which means that threads may share the module and
connections, but not cursors. Sharing means that a thread may use a
resource without wrapping it using a mutex semaphore to implement resource
locking.
Note that in order to make use of multiple threads in a program which
intends to connect and disconnect in different threads, the threaded
parameter to :meth:`connect()` or :meth:`SessionPool()` must be true.
.. data:: version
.. data:: __version__
String constant stating the version of the module. Currently '|release|'.
.. note::
This attribute is an extension to the DB API definition.
Advanced Queuing: Delivery Modes
--------------------------------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`~DeqOptions.deliverymode` attribute of the
:ref:`dequeue options object <deqoptions>` passed as the options parameter to
the :meth:`Connection.deq()` method as well as the
:attr:`~EnqOptions.deliverymode` attribute of the
:ref:`enqueue options object <enqoptions>` passed as the options parameter to
the :meth:`Connection.enq()` method. They are also possible values for the
:attr:`~MessageProperties.deliverymode` attribute of the
:ref:`message properties object <msgproperties>` passed as the msgproperties
parameter to the :meth:`Connection.deq()` and :meth:`Connection.enq()` methods.
.. data:: MSG_BUFFERED
This constant is used to specify that enqueue/dequeue operations should
enqueue or dequeue buffered messages.
.. data:: MSG_PERSISTENT
This constant is used to specify that enqueue/dequeue operations should
enqueue or dequeue persistent messages. This is the default value.
.. data:: MSG_PERSISTENT_OR_BUFFERED
This constant is used to specify that dequeue operations should dequeue
either persistent or buffered messages.
Advanced Queuing: Dequeue Modes
-------------------------------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`~DeqOptions.mode` attribute of the
:ref:`dequeue options object <deqoptions>`. This object is the options
parameter for the :meth:`Connection.deq()` method.
.. data:: DEQ_BROWSE
This constant is used to specify that dequeue should read the message
without acquiring any lock on the message (equivalent to a select
statement).
.. data:: DEQ_LOCKED
This constant is used to specify that dequeue should read and obtain a
write lock on the message for the duration of the transaction (equivalent
to a select for update statement).
.. data:: DEQ_REMOVE
This constant is used to specify that dequeue should read the message and
update or delete it. This is the default value.
.. data:: DEQ_REMOVE_NODATA
This constant is used to specify that dequeue should confirm receipt of the
message but not deliver the actual message content.
Advanced Queuing: Dequeue Navigation Modes
------------------------------------------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`~DeqOptions.navigation` attribute of the
:ref:`dequeue options object <deqoptions>`. This object is the options
parameter for the :meth:`Connection.deq()` method.
.. data:: DEQ_FIRST_MSG
This constant is used to specify that dequeue should retrieve the first
available message that matches the search criteria. This resets the
position to the beginning of the queue.
.. data:: DEQ_NEXT_MSG
This constant is used to specify that dequeue should retrieve the next
available message that matches the search criteria. If the previous message
belongs to a message group, AQ retrieves the next available message that
matches the search criteria and belongs to the message group. This is the
default.
.. data:: DEQ_NEXT_TRANSACTION
This constant is used to specify that dequeue should skip the remainder of
the transaction group and retrieve the first message of the next
transaction group. This option can only be used if message grouping is
enabled for the current queue.
Advanced Queuing: Dequeue Visibility Modes
------------------------------------------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`~DeqOptions.visibility` attribute of the
:ref:`dequeue options object <deqoptions>`. This object is the options
parameter for the :meth:`Connection.deq()` method.
.. data:: DEQ_IMMEDIATE
This constant is used to specify that dequeue should perform its work as
part of an independent transaction.
.. data:: DEQ_ON_COMMIT
This constant is used to specify that dequeue should be part of the current
transaction. This is the default value.
Advanced Queuing: Dequeue Wait Modes
------------------------------------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`~DeqOptions.wait` attribute of the
:ref:`dequeue options object <deqoptions>`. This object is the options
parameter for the :meth:`Connection.deq()` method.
.. data:: DEQ_NO_WAIT
This constant is used to specify that dequeue not wait for messages to be
available for dequeuing.
.. data:: DEQ_WAIT_FOREVER
This constant is used to specify that dequeue should wait forever for
messages to be available for dequeuing. This is the default value.
Advanced Queuing: Enqueue Visibility Modes
------------------------------------------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`~EnqOptions.visibility` attribute of the
:ref:`enqueue options object <enqoptions>`. This object is the options
parameter for the :meth:`Connection.enq()` method.
.. data:: ENQ_IMMEDIATE
This constant is used to specify that enqueue should perform its work as
part of an independent transaction.
.. data:: ENQ_ON_COMMIT
This constant is used to specify that enqueue should be part of the current
transaction. This is the default value.
Advanced Queuing: Message States
--------------------------------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`~MessageProperties.state` attribute of the
:ref:`message properties object <msgproperties>`. This object is the
msgproperties parameter for the :meth:`Connection.deq()` and
:meth:`Connection.enq()` methods.
.. data:: MSG_EXPIRED
This constant is used to specify that the message has been moved to the
exception queue.
.. data:: MSG_PROCESSED
This constant is used to specify that the message has been processed and
has been retained.
.. data:: MSG_READY
This constant is used to specify that the message is ready to be processed.
.. data:: MSG_WAITING
This constant is used to specify that the message delay has not yet been
reached.
Advanced Queuing: Other
-----------------------
These constants are extensions to the DB API definition. They are special
constants used in advanced queuing.
.. data:: MSG_NO_DELAY
This constant is a possible value for the :attr:`~MessageProperties.delay`
attribute of the :ref:`message properties object <msgproperties>` passed
as the msgproperties parameter to the :meth:`Connection.deq()` and
:meth:`Connection.enq()` methods. It specifies that no delay should be
imposed and the message should be immediately available for dequeuing. This
is also the default value.
.. data:: MSG_NO_EXPIRATION
This constant is a possible value for the
:attr:`~MessageProperties.expiration` attribute of the
:ref:`message properties object <msgproperties>` passed as the msgproperties
parameter to the :meth:`Connection.deq()` and :meth:`Connection.enq()`
methods. It specifies that the message never expires. This is also the
default value.
.. _connection-authorization-modes:
Connection Authorization Modes
------------------------------
These constants are extensions to the DB API definition. They are possible
values for the mode parameter of the :meth:`connect()` method.
.. data:: DEFAULT_AUTH
This constant is used to specify that default authentication is to take
place. This is the default value if no mode is passed at all.
.. versionadded:: 7.2
.. data:: PRELIM_AUTH
This constant is used to specify that preliminary authentication is to be
used. This is needed for performing database startup and shutdown.
.. data:: SYSASM
This constant is used to specify that SYSASM access is to be acquired.
.. data:: SYSBKP
This constant is used to specify that SYSBACKUP access is to be acquired.
.. data:: SYSDBA
This constant is used to specify that SYSDBA access is to be acquired.
.. data:: SYSDGD
This constant is used to specify that SYSDG access is to be acquired.
.. data:: SYSKMT
This constant is used to specify that SYSKM access is to be acquired.
.. data:: SYSOPER
This constant is used to specify that SYSOPER access is to be acquired.
.. data:: SYSRAC
This constant is used to specify that SYSRAC access is to be acquired.
Database Shutdown Modes
-----------------------
These constants are extensions to the DB API definition. They are possible
values for the mode parameter of the :meth:`Connection.shutdown()` method.
.. data:: DBSHUTDOWN_ABORT
This constant is used to specify that the caller should not wait for
current processing to complete or for users to disconnect from the
database. This should only be used in unusual circumstances since database
recovery may be necessary upon next startup.
.. data:: DBSHUTDOWN_FINAL
This constant is used to specify that the instance can be truly halted.
This should only be done after the database has been shutdown with one of
the other modes (except abort) and the database has been closed and
dismounted using the appropriate SQL commands.
.. data:: DBSHUTDOWN_IMMEDIATE
This constant is used to specify that all uncommitted transactions should
be rolled back and any connected users should be disconnected.
.. data:: DBSHUTDOWN_TRANSACTIONAL
This constant is used to specify that further connections to the database
should be prohibited and no new transactions should be allowed. It then
waits for all active transactions to complete.
.. data:: DBSHUTDOWN_TRANSACTIONAL_LOCAL
This constant is used to specify that further connections to the database
should be prohibited and no new transactions should be allowed. It then
waits for only local active transactions to complete.
Event Types
-----------
These constants are extensions to the DB API definition. They are possible
values for the :attr:`Message.type` attribute of the messages that are sent
for subscriptions created by the :meth:`Connection.subscribe()` method.
.. data:: EVENT_AQ
This constant is used to specify that one or more messages are available
for dequeuing on the queue specified when the subscription was created.
.. data:: EVENT_DEREG
This constant is used to specify that the subscription has been
deregistered and no further notifications will be sent.
.. data:: EVENT_NONE
This constant is used to specify no information is available about the
event.
.. data:: EVENT_OBJCHANGE
This constant is used to specify that a database change has taken place on
a table registered with the :meth:`Subscription.registerquery()` method.
.. data:: EVENT_QUERYCHANGE
This constant is used to specify that the result set of a query registered
with the :meth:`Subscription.registerquery()` method has been changed.
.. data:: EVENT_SHUTDOWN
This constant is used to specify that the instance is in the process of
being shut down.
.. data:: EVENT_SHUTDOWN_ANY
This constant is used to specify that any instance (when running RAC) is in
the process of being shut down.
.. data:: EVENT_STARTUP
This constant is used to specify that the instance is in the process of
being started up.
.. _cqn-operation-codes:
Operation Codes
---------------
These constants are extensions to the DB API definition. They are possible
values for the operations parameter for the :meth:`Connection.subscribe()`
method. One or more of these values can be OR'ed together. These values are
also used by the :attr:`MessageTable.operation` or
:attr:`MessageQuery.operation` attributes of the messages that are sent.
.. data:: OPCODE_ALLOPS
This constant is used to specify that messages should be sent for all
operations.
.. data:: OPCODE_ALLROWS
This constant is used to specify that the table or query has been
completely invalidated.
.. data:: OPCODE_ALTER
This constant is used to specify that messages should be sent when a
registered table has been altered in some fashion by DDL, or that the
message identifies a table that has been altered.
.. data:: OPCODE_DELETE
This constant is used to specify that messages should be sent when data is
deleted, or that the message identifies a row that has been deleted.
.. data:: OPCODE_DROP
This constant is used to specify that messages should be sent when a
registered table has been dropped, or that the message identifies a table
that has been dropped.
.. data:: OPCODE_INSERT
This constant is used to specify that messages should be sent when data is
inserted, or that the message identifies a row that has been inserted.
.. data:: OPCODE_UPDATE
This constant is used to specify that messages should be sent when data is
updated, or that the message identifies a row that has been updated.
.. _sesspoolmodes:
Session Pool Get Modes
----------------------
These constants are extensions to the DB API definition. They are possible
values for the getmode parameter of the :meth:`SessionPool()` method.
.. data:: SPOOL_ATTRVAL_FORCEGET
This constant is used to specify that a new connection will be returned if
there are no free sessions available in the pool.
.. data:: SPOOL_ATTRVAL_NOWAIT
This constant is used to specify that an exception should be raised if
there are no free sessions available in the pool. This is the default
value.
.. data:: SPOOL_ATTRVAL_WAIT
This constant is used to specify that the caller should wait until a
session is available if there are no free sessions available in the pool.
.. data:: SPOOL_ATTRVAL_TIMEDWAIT
This constant is used to specify that the caller should wait for a period
of time (defined by the waitTimeout parameter) for a session to become
available before returning with an error.
Session Pool Purity
-------------------
These constants are extensions to the DB API definition. They are possible
values for the purity parameter of the :meth:`connect()` method, which is used
in database resident connection pooling (DRCP).
.. data:: ATTR_PURITY_DEFAULT
This constant is used to specify that the purity of the session is the
default value identified by Oracle (see Oracle's documentation for more
information). This is the default value.
.. data:: ATTR_PURITY_NEW
This constant is used to specify that the session acquired from the pool
should be new and not have any prior session state.
.. data:: ATTR_PURITY_SELF
This constant is used to specify that the session acquired from the pool
need not be new and may have prior session state.
Subscription Grouping Classes
-----------------------------
These constants are extensions to the DB API definition. They are possible
values for the groupingClass parameter of the :meth:`Connection.subscribe()`
method.
.. data:: SUBSCR_GROUPING_CLASS_TIME
This constant is used to specify that events are to be grouped by the
period of time in which they are received.
Subscription Grouping Types
---------------------------
These constants are extensions to the DB API definition. They are possible
values for the groupingType parameter of the :meth:`Connection.subscribe()`
method.
.. data:: SUBSCR_GROUPING_TYPE_SUMMARY
This constant is used to specify that when events are grouped a summary of
the events should be sent instead of the individual events. This is the
default value.
.. data:: SUBSCR_GROUPING_TYPE_LAST
This constant is used to specify that when events are grouped the last
event that makes up the group should be sent instead of the individual
events.
.. _subscr-namespaces:
Subscription Namespaces
-----------------------
These constants are extensions to the DB API definition. They are possible
values for the namespace parameter of the :meth:`Connection.subscribe()`
method.
.. data:: SUBSCR_NAMESPACE_AQ
This constant is used to specify that notifications should be sent when a
queue has messages available to dequeue.
.. data:: SUBSCR_NAMESPACE_DBCHANGE
This constant is used to specify that database change notification or query
change notification messages are to be sent. This is the default value.
.. _subscr-protocols:
Subscription Protocols
----------------------
These constants are extensions to the DB API definition. They are possible
values for the protocol parameter of the :meth:`Connection.subscribe()` method.
.. data:: SUBSCR_PROTO_HTTP
This constant is used to specify that notifications will be sent to an
HTTP URL when a message is generated. This value is currently not
supported.
.. data:: SUBSCR_PROTO_MAIL
This constant is used to specify that notifications will be sent to an
e-mail address when a message is generated. This value is currently not
supported.
.. data:: SUBSCR_PROTO_OCI
This constant is used to specify that notifications will be sent to the
callback routine identified when the subscription was created. It is the
default value and the only value currently supported.
.. data:: SUBSCR_PROTO_SERVER
This constant is used to specify that notifications will be sent to a
PL/SQL procedure when a message is generated. This value is currently not
supported.
.. _subscr-qos:
Subscription Quality of Service
-------------------------------
These constants are extensions to the DB API definition. They are possible
values for the qos parameter of the :meth:`Connection.subscribe()` method. One
or more of these values can be OR'ed together.
.. data:: SUBSCR_QOS_BEST_EFFORT
This constant is used to specify that best effort filtering for query
result set changes is acceptable. False positive notifications may be
received. This behaviour may be suitable for caching applications.
.. data:: SUBSCR_QOS_DEREG_NFY
This constant is used to specify that the subscription should be
automatically unregistered after the first notification is received.
.. data:: SUBSCR_QOS_QUERY
This constant is used to specify that notifications should be sent if the
result set of the registered query changes. By default no false positive
notifications will be generated.
.. data:: SUBSCR_QOS_RELIABLE
This constant is used to specify that notifications should not be lost in
the event of database failure.
.. data:: SUBSCR_QOS_ROWIDS
This constant is used to specify that the rowids of the inserted, updated
or deleted rows should be included in the message objects that are sent.
.. _types:
DB API Types
------------
.. data:: BINARY
This type object is used to describe columns in a database that contain
binary data. The database types :data:`DB_TYPE_RAW` and
:data:`DB_TYPE_LONG_RAW` will compare equal to this value. If a variable is
created with this type, the database type :data:`DB_TYPE_RAW` will be used.
.. data:: DATETIME
This type object is used to describe columns in a database that are dates.
The database types :data:`DB_TYPE_DATE`, :data:`DB_TYPE_TIMESTAMP`,
:data:`DB_TYPE_TIMESTAMP_LTZ` and :data:`DB_TYPE_TIMESTAMP_TZ` will all
compare equal to this value. If a variable is created with this
type, the database type :data:`DB_TYPE_DATE` will be used.
.. data:: NUMBER
This type object is used to describe columns in a database that are
numbers. The database types :data:`DB_TYPE_BINARY_DOUBLE`,
:data:`DB_TYPE_BINARY_FLOAT`, :data:`DB_TYPE_BINARY_INTEGER` and
:data:`DB_TYPE_NUMBER` will all compare equal to this value. If a variable
is created with this type, the database type :data:`DB_TYPE_NUMBER` will be
used.
.. data:: ROWID
This type object is used to describe the pseudo column "rowid". The
database type :data:`DB_TYPE_ROWID` will compare equal to this value. If a
variable is created with this type, the database type
:data:`DB_TYPE_VARCHAR` will be used.
.. data:: STRING
This type object is used to describe columns in a database that are
strings. The database types :data:`DB_TYPE_CHAR`, :data:`DB_TYPE_LONG`,
:data:`DB_TYPE_NCHAR`, :data:`DB_TYPE_NVARCHAR` and :data:`DB_TYPE_VARCHAR`
will all compare equal to this value. If a variable is created with this
type, the database type :data:`DB_TYPE_VARCHAR` will be used.
.. _dbtypes:
Database Types
--------------
All of these types are extensions to the DB API definition. They are found in
query and object metadata. They can also be used to specify the database type
when binding data.
.. data:: DB_TYPE_BFILE
Describes columns, attributes or array elements in a database that are of
type BFILE. It will compare equal to the DB API type :data:`BINARY`.
.. data:: DB_TYPE_BINARY_DOUBLE
Describes columns, attributes or array elements in a database that are of
type BINARY_DOUBLE. It will compare equal to the DB API type
:data:`NUMBER`.
.. data:: DB_TYPE_BINARY_FLOAT
Describes columns, attributes or array elements in a database that are
of type BINARY_FLOAT. It will compare equal to the DB API type
:data:`NUMBER`.
.. data:: DB_TYPE_BINARY_INTEGER
Describes attributes or array elements in a database that are of type
BINARY_INTEGER. It will compare equal to the DB API type :data:`NUMBER`.
.. data:: DB_TYPE_BLOB
Describes columns, attributes or array elements in a database that are of
type BLOB. It will compare equal to the DB API type :data:`BINARY`.
.. data:: DB_TYPE_BOOLEAN
Describes attributes or array elements in a database that are of type
BOOLEAN. It is only available in Oracle 12.1 and higher and only within
PL/SQL.
.. data:: DB_TYPE_CHAR
Describes columns, attributes or array elements in a database that are of
type CHAR. It will compare equal to the DB API type :data:`STRING`.
Note that these are fixed length string values and behave differently from
VARCHAR2.
.. data:: DB_TYPE_CLOB
Describes columns, attributes or array elements in a database that are of
type CLOB. It will compare equal to the DB API type :data:`STRING`.
.. data:: DB_TYPE_CURSOR
Describes columns in a database that are of type CURSOR. In PL/SQL these
are knoown as REF CURSOR.
.. data:: DB_TYPE_DATE
Describes columns, attributes or array elements in a database that are of
type DATE. It will compare equal to the DB API type :data:`DATETIME`.
.. data:: DB_TYPE_INTERVAL_DS
Describes columns, attributes or array elements in a database that are of
type INTERVAL DAY TO SECOND.
.. data:: DB_TYPE_INTERVAL_YM
Describes columns, attributes or array elements in a database that are of
type INTERVAL YEAR TO MONTH. This database type is not currently supported
by cx_Oracle.
.. data:: DB_TYPE_LONG
Describes columns, attributes or array elements in a database that are of
type LONG. It will compare equal to the DB API type :data:`STRING`.
.. data:: DB_TYPE_LONG_RAW
Describes columns, attributes or array elements in a database that are of
type LONG RAW. It will compare equal to the DB API type :data:`BINARY`.
.. data:: DB_TYPE_NCHAR
Describes columns, attributes or array elements in a database that are of
type NCHAR. It will compare equal to the DB API type :data:`STRING`.
Note that these are fixed length string values and behave differently from
NVARCHAR2.
.. data:: DB_TYPE_NCLOB
Describes columns, attributes or array elements in a database that are of
type NCLOB. It will compare equal to the DB API type :data:`STRING`.
.. data:: DB_TYPE_NUMBER
Describes columns, attributes or array elements in a database that are of
type NUMBER. It will compare equal to the DB API type :data:`NUMBER`.
.. data:: DB_TYPE_NVARCHAR
Describes columns, attributes or array elements in a database that are of
type NVARCHAR2. It will compare equal to the DB API type :data:`STRING`.
.. data:: DB_TYPE_OBJECT
Describes columns, attributes or array elements in a database that are an
instance of a named SQL or PL/SQL type.
.. data:: DB_TYPE_RAW
Describes columns, attributes or array elements in a database that are of
type RAW. It will compare equal to the DB API type :data:`BINARY`.
.. data:: DB_TYPE_ROWID
Describes columns, attributes or array elements in a database that are of
type ROWID or UROWID. It will compare equal to the DB API type
:data:`ROWID`.
.. data:: DB_TYPE_TIMESTAMP
Describes columns, attributes or array elements in a database that are of
type TIMESTAMP. It will compare equal to the DB API type :data:`DATETIME`.
.. data:: DB_TYPE_TIMESTAMP_LTZ
Describes columns, attributes or array elements in a database that are of
type TIMESTAMP WITH LOCAL TIME ZONE. It will compare equal to the DB API
type :data:`DATETIME`.
.. data:: DB_TYPE_TIMESTAMP_TZ
Describes columns, attributes or array elements in a database that are of
type TIMESTAMP WITH TIME ZONE. It will compare equal to the DB API type
:data:`DATETIME`.
.. data:: DB_TYPE_VARCHAR
Describes columns, attributes or array elements in a database that are of
type VARCHAR2. It will compare equal to the DB API type :data:`STRING`.
.. _dbtypesynonyms:
Database Type Synonyms
----------------------
All of the following constants are deprecated and will be removed in a future
version of cx_Oracle.
.. data:: BFILE
A synonym for :data:`DB_TYPE_BFILE`.
.. deprecated:: 8.0
.. data:: BLOB
A synonym for :data:`DB_TYPE_BLOB`.
.. deprecated:: 8.0
.. data:: BOOLEAN
A synonym for :data:`DB_TYPE_BOOLEAN`.
.. deprecated:: 8.0
.. data:: CLOB
A synonym for :data:`DB_TYPE_CLOB`.
.. deprecated:: 8.0
.. data:: CURSOR
A synonym for :data:`DB_TYPE_CURSOR`.
.. deprecated:: 8.0
.. data:: FIXED_CHAR
A synonym for :data:`DB_TYPE_CHAR`.
.. deprecated:: 8.0
.. data:: FIXED_NCHAR
A synonym for :data:`DB_TYPE_NCHAR`.
.. deprecated:: 8.0
.. data:: INTERVAL
A synonym for :data:`DB_TYPE_INTERVAL_DS`.
.. deprecated:: 8.0
.. data:: LONG_BINARY
A synonym for :data:`DB_TYPE_LONG_RAW`.
.. deprecated:: 8.0
.. data:: LONG_STRING
A synonym for :data:`DB_TYPE_LONG`.
.. deprecated:: 8.0
.. data:: NATIVE_FLOAT
A synonym for :data:`DB_TYPE_BINARY_DOUBLE`.
.. deprecated:: 8.0
.. data:: NATIVE_INT
A synonym for :data:`DB_TYPE_BINARY_INTEGER`.
.. deprecated:: 8.0
.. data:: NCHAR
A synonym for :data:`DB_TYPE_NVARCHAR`.
.. deprecated:: 8.0
.. data:: NCLOB
A synonym for :data:`DB_TYPE_NCLOB`.
.. deprecated:: 8.0
.. data:: OBJECT
A synonym for :data:`DB_TYPE_OBJECT`.
.. deprecated:: 8.0
.. data:: TIMESTAMP
A synonym for :data:`DB_TYPE_TIMESTAMP`.
.. deprecated:: 8.0
Other Types
-----------
All of these types are extensions to the DB API definition.
.. data:: ApiType
This type object is the Python type of the database API type constants
:data:`BINARY`, :data:`DATETIME`, :data:`NUMBER`, :data:`ROWID` and
:data:`STRING`.
.. data:: DbType
This type object is the Python type of the
:ref:`database type constants <dbtypes>`.
.. data:: LOB
This type object is the Python type of :data:`DB_TYPE_BLOB`,
:data:`DB_TYPE_BFILE`, :data:`DB_TYPE_CLOB` and :data:`DB_TYPE_NCLOB` data
that is returned from cursors.
.. _exceptions:
Exceptions
==========
.. exception:: Warning
Exception raised for important warnings and defined by the DB API but not
actually used by cx_Oracle.
.. exception:: Error
Exception that is the base class of all other exceptions defined by
cx_Oracle and is a subclass of the Python StandardError exception (defined
in the module exceptions).
.. exception:: InterfaceError
Exception raised for errors that are related to the database interface
rather than the database itself. It is a subclass of Error.
.. exception:: DatabaseError
Exception raised for errors that are related to the database. It is a
subclass of Error.
.. exception:: DataError
Exception raised for errors that are due to problems with the processed
data. It is a subclass of DatabaseError.
.. exception:: OperationalError
Exception raised for errors that are related to the operation of the
database but are not necessarily under the control of the programmer. It is
a subclass of DatabaseError.
.. exception:: IntegrityError
Exception raised when the relational integrity of the database is affected.
It is a subclass of DatabaseError.
.. exception:: InternalError
Exception raised when the database encounters an internal error. It is a
subclass of DatabaseError.
.. exception:: ProgrammingError
Exception raised for programming errors. It is a subclass of DatabaseError.
.. exception:: NotSupportedError
Exception raised when a method or database API was used which is not
supported by the database. It is a subclass of DatabaseError.
.. _exchandling:
Exception handling
==================
.. note::
PEP 249 (Python Database API Specification v2.0) says the following about
exception values:
[...] The values of these exceptions are not defined. They should
give the user a fairly good idea of what went wrong, though. [...]
With cx_Oracle every exception object has exactly one argument in the
``args`` tuple. This argument is a ``cx_Oracle._Error`` object which has
the following five read-only attributes.
.. attribute:: _Error.code
Integer attribute representing the Oracle error number (ORA-XXXXX).
.. attribute:: _Error.offset
Integer attribute representing the error offset when applicable.
.. attribute:: _Error.message
String attribute representing the Oracle message of the error. This
message is localized by the environment of the Oracle connection.
.. attribute:: _Error.context
String attribute representing the context in which the exception was
raised.
.. attribute:: _Error.isrecoverable
Boolean attribute representing whether the error is recoverable or not.
This is False in all cases unless both Oracle Database 12.1 (or later) and
Oracle Client 12.1 (or later) are being used.
.. versionadded:: 5.3
This allows you to use the exceptions for example in the following way:
::
import cx_Oracle
connection = cx_Oracle.connect("cx_Oracle/dev@localhost/orclpdb1")
cursor = connection.cursor()
try:
cursor.execute("select 1 / 0 from dual")
except cx_Oracle.DatabaseError as exc:
error, = exc.args
print("Oracle-Error-Code:", error.code)
print("Oracle-Error-Message:", error.message)
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