[3.0.x] Fixed #30928 -- Clarified MySQL/MariaDB support of QuerySet.select_for_update() options.

Thanks Par Andersson for reporting the issue.

Backport of d94d7b113c from master
This commit is contained in:
kola-er 2019-11-04 22:44:10 +01:00 committed by Mariusz Felisiak
parent 78fc05303a
commit a5b4a909f0
2 changed files with 14 additions and 6 deletions

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@ -625,10 +625,17 @@ 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``, ``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.
MySQL and MariaDB do not support some options to the ``SELECT ... FOR UPDATE``
statement. If ``select_for_update()`` is used with an unsupported option, then
a :exc:`~django.db.NotSupportedError` is raised.
=============== ========= ==========
Option MariaDB MySQL
=============== ========= ==========
``SKIP LOCKED`` X (≥8.0.1)
``NOWAIT`` X (≥10.3) X (≥8.0.1)
``OF``
=============== ========= ==========
When using ``select_for_update()`` on MySQL, make sure you filter a queryset
against at least set of fields contained in unique constraints or only against

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@ -1706,8 +1706,9 @@ them::
<QuerySet [<Person: ...)>, ...]>
Currently, the ``postgresql``, ``oracle``, and ``mysql`` database
backends support ``select_for_update()``. However, MySQL doesn't support the
``nowait``, ``skip_locked``, and ``of`` arguments.
backends support ``select_for_update()``. However, MariaDB 10.3+ supports only
the ``nowait`` argument and MySQL 8.0.1+ supports the ``nowait`` and
``skip_locked`` arguments. MySQL and MariaDB don't support the ``of`` argument.
Passing ``nowait=True``, ``skip_locked=True``, or ``of`` to
``select_for_update()`` using database backends that do not support these