Sorry for the late response.
Maybe it's sufficient to override the QuerySet clone method to just return
self, not really clone it.
2011/2/14 myx <i.virab...@gmail.com>
> Thank you for the reply. But I meant a slightly different case:
>
> Item.objects.filter(...).order_by(...).values_list('id', flat=True)[:
> 10]
>
> As you can see, there are four cloning operations. Wouldn't be
> chaining possible without cloning the queryset? The method could just
> return the original queryset. Seems like I'll have to write raw
> queries in such cases :(
>
> On Feb 11, 1:18 pm, kurvenschubser <malte.engelha...@gmx.net> wrote:
> > Hi myx,
> >
> > cloning is useful for chaining of filters, e.g.
> >
> User.objects.filter(name="Harry").exclude(lastname="Potter").filter(somethi
> ngelse="bla")
> >
> > But most of the time, I found I can construct querysets using a
> > dictionary for collecting the query conditions:
> >
> > d = {name:"Harry", lastname:"Potter", somethingelse:"bla"}
> > User.objects.filter(**d)
> >
> > For more complex queries, e.g.
> >
> > if not d:
> > return
> >
> > q0 = Q(**dict(d.popitem()))
> >
> > for i, (k, v) in enumerate(d.items()):
> > qx = Q(**{k:v})
> > if i % 2:
> > q0 | qx
> > else:
> > q0 & qx
> >
> > User.objects.filter(q0)
> >
> > On 10 Feb., 10:55, myx <i.virab...@gmail.com> wrote:
> >
> >
> >
> >
> >
> >
> >
> > > Almost every method of QuerySet clones it. Sometimes it is very
> > > ineficcient, for example when querysets are constructed in loops. I
> > > have a function, which makes about 20 queries, and its execution time
> > > is about 100ms. After profiling the function, I saw that clone() takes
> > > most of the time: 70ms. It is called about 60 times, 1ms per call. The
> > > queries themselves are very fast (about 15ms for all queries). So
> > > constructing the query takes much longer time than executing it.
> > > What cloning is needed for? Can I prevent queryset from cloning, or do
> > > something else to reduce cpu consumption?
>
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