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Fixed #28010 -- Added FOR UPDATE OF support to QuerySet.select_for_update().

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Ran Benita 2017-06-29 23:00:15 +03:00 • committed by Tim Graham
parent 2d18c60fbb
commit b9f7dce84b
12 changed files with 206 additions and 23 deletions
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6
docs/ref/databases.txt
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@ -629,9 +629,9 @@ both MySQL and Django will attempt to convert the values from UTC to local time.
Row locking with ``QuerySet.select_for_update()``
-------------------------------------------------
MySQL does not support the ``NOWAIT`` and ``SKIP LOCKED`` options to the
``SELECT ... FOR UPDATE`` statement. If ``select_for_update()`` is used with
``nowait=True`` or ``skip_locked=True``, then a
MySQL does not support the ``NOWAIT``, ``SKIP LOCKED``, and ``OF`` options to
the ``SELECT ... FOR UPDATE`` statement. If ``select_for_update()`` is used
with ``nowait=True``, ``skip_locked=True``, or ``of`` then a
:exc:`~django.db.NotSupportedError` is raised.
Automatic typecasting can cause unexpected results

23
docs/ref/models/querysets.txt
View file

@ -1611,7 +1611,7 @@ For example::
``select_for_update()``
~~~~~~~~~~~~~~~~~~~~~~~
.. method:: select_for_update(nowait=False, skip_locked=False)
.. method:: select_for_update(nowait=False, skip_locked=False, of=())
Returns a queryset that will lock rows until the end of the transaction,
generating a ``SELECT ... FOR UPDATE`` SQL statement on supported databases.
@ -1635,14 +1635,21 @@ queryset is evaluated. You can also ignore locked rows by using
``select_for_update()`` with both options enabled will result in a
:exc:`ValueError`.
By default, ``select_for_update()`` locks all rows that are selected by the
query. For example, rows of related objects specified in :meth:`select_related`
are locked in addition to rows of the queryset's model. If this isn't desired,
specify the related objects you want to lock in ``select_for_update(of=(...))``
using the same fields syntax as :meth:`select_related`. Use the value ``'self'``
to refer to the queryset's model.
Currently, the ``postgresql``, ``oracle``, and ``mysql`` database
backends support ``select_for_update()``. However, MySQL doesn't support the
``nowait`` and ``skip_locked`` arguments.
``nowait``, ``skip_locked``, and ``of`` arguments.
Passing ``nowait=True`` or ``skip_locked=True`` to ``select_for_update()``
using database backends that do not support these options, such as MySQL,
raises a :exc:`~django.db.NotSupportedError`. This prevents code from
unexpectedly blocking.
Passing ``nowait=True``, ``skip_locked=True``, or ``of`` to
``select_for_update()`` using database backends that do not support these
options, such as MySQL, raises a :exc:`~django.db.NotSupportedError`. This
prevents code from unexpectedly blocking.
Evaluating a queryset with ``select_for_update()`` in autocommit mode on
backends which support ``SELECT ... FOR UPDATE`` is a
@ -1670,6 +1677,10 @@ raised if ``select_for_update()`` is used in autocommit mode.
The ``skip_locked`` argument was added.
.. versionchanged:: 2.0
The ``of`` argument was added.
``raw()``
~~~~~~~~~