""" I also noticed in db optimization docs that we have explicitly documented update() and delete() as bypassing signals, and I think we should honour that.
https://docs.djangoproject.com/en/dev/topics/db/optimization/#use-queryset-update-and-delete """ Is this correct for delete? A quick test (A1 is a model which I have hanging around - details about it aren't important): from django.db.models.signals import post_delete def foo(*args, **kwargs): print args, kwargs post_delete.connect(foo, sender=A1) A1(dt=datetime.now()).save() A1.objects.all().delete() Result: () {'instance': <A1: A1 object>, 'signal': <django.dispatch.dispatcher.Signal object at 0xa47434c>, 'sender': <class 'obj_creation_speed.models.A1'>, 'using': 'default'} Search post_delete in django/db/models/deletion.py. Signals seem to be sent, even for cascaded deletion. Personally I don't think post/pre instance changed signals are the way to go if you want to do auditing. DB triggers are much more reliable. Some problems with the Django signals: - All operations do not send signals (bulk_create could easily send signals, the instances are available directly in that case, even bulk update could send signals per instance - first check if there is a listener, if there is, fetch all the updated instances and send signals, if there isn't, then don't fetch the instances. You will only pay the price when needed. Not saying this is a great idea, but maybe worth a thought). - Proxy (including deferred models) and multitable-inherited models do not send signals as you would expect. I have groundwork for how to implement fast inherited signals in ticket #16679. The patch in that ticket also makes model __init__ much faster in certain common-enough cases. On the other hand, yet another cache. - If you do anything outside Django Models (raw SQL, dbshell, another application accessing the DB) your auditing will not work. - The DB triggers approach is faster. The downside is that you will be programming DB specific triggers, in DB-specific language. Schema upgrades are a nightmare. - Anssi Kääriäinen -- You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com. To unsubscribe from this group, send email to django-developers+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-developers?hl=en.
