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Added another bit to the update() queryset docs about avoiding race conditions 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16517 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Adrian Holovaty 2011-07-05 20:16:08 +00:00
parent 8b34a01017
commit 471a841147
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docs/ref/models/querysets.txt
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@ -1328,6 +1328,10 @@ memory. The former is more efficient. For example, instead of doing this::
Entry.objects.get(id=10).update(comments_on=False) Entry.objects.get(id=10).update(comments_on=False)
Using ``update()`` instead of loading the object into memory also prevents a
race condition where something might change in your database in the short
period of time between loading the object and calling ``save()``.
Finally, note that the ``update()`` method does an update at the SQL level and, Finally, note that the ``update()`` method does an update at the SQL level and,
thus, does not call any ``save()`` methods on your models, nor does it emit the thus, does not call any ``save()`` methods on your models, nor does it emit the
``pre_save`` or ``post_save`` signals (which are a consequence of calling ``pre_save`` or ``post_save`` signals (which are a consequence of calling