On Sun, Sep 19, 2010 at 11:41 AM, Alex Gaynor <alex.gay...@gmail.com> wrote:
> On Sun, Sep 19, 2010 at 10:28 AM, drakkan <drakkan1...@gmail.com> wrote: > > in my opinion django should emulate "ON DELETE CASCADE" only on > > database backends that doesn't support it, if you are using a database > > such as postgres delete() on a queryset should issue a single sql > > query and should be the database to care about the cascade/set null > > etc.. behaviour > > > > http://code.djangoproject.com/ticket/7539 > > > > I think this way django could archive the best performance, > > > > if one need to delete a lot of row and there are relations to other > > tables a single raw SQL query is not enough, you need to modify the > > database schema too to ensure the correct cascade behaviuor or you > > need to issue an sql query for every related table > > > We also support cascading generic relationships, which no database > supports. > And currently the pre- and post-delete signals are called for each object, even in a bulk delete, so changing that would be a backwards-incompatible change. I don't much like that it does this, but changing it would still undoubtedly cause trouble for some people. That said, queryset.update() does NOT iterate through all the objects in a queryset and call save(), and nor does it call the pre- and post-save signals. [1] We have two bulk operations that behave differently; would it be worthwhile, at least, to make the behavior configurable? Tobias [1] http://docs.djangoproject.com/en/dev/topics/db/queries/#updating-multiple-objects-at-once -- Tobias McNulty, Managing Partner Caktus Consulting Group, LLC http://www.caktusgroup.com -- You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-develop...@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.
