It has been brought to my attention that the specific ordering of
order_by is potentially different for different backends; it seems
that it must be sent to the database for consistency - in other words:
qs = Model.objects.all()
# ...something that evaluates qs
qs.objects.order_by('field') # these two should
Model.objects.order_by('field') # always be the same
So the parallel implementation problem comes out here. But at least
filter(), exclude(), and values() can be done without requiring new
database traffic.
On Apr 15, 7:33 pm, Travis Parker <[EMAIL PROTECTED]> wrote:
> > Because every time you modify a QuerySet you are changing the results
> > that will be returned. Calling filter() will restrict the results.
> > Calling order_by() will change the order the results are returned in.
> > And so on. Thus, the cache of the queyrset that was cloned is invalid
> > for the new queryset.
>
> But in most of the queryset-returning methods, the changes to the
> results don't result in any data that wasn't already there, just a
> subset or reordering of already-fetched results. The cloned queryset's
> cache isn't invalid - it is a superset of the clone's cache, so why
> should we have to go back to the database again? That's unnecessary
> traffic.
>
>
>
> > If you already have the results in the cache and you know that your
> > modifications to the queryset could just as easily be done in Python,
> > then just do them in Python yourself.
>
> That's what I've done this time - next time it would be nice if django
> did it for me. I shouldn't have to go outside of django's ORM just to
> avoid unnecessary database traffic.
>
>
>
> > Regards,
> > Malcolm
>
> > --
> > Atheism is a non-prophet organization.http://www.pointy-stick.com/blog/
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