On Wed, Nov 2, 2011 at 6:26 PM, Ian Clelland wrote:
> Just looking at the source to QuerySet (finally), and it looks like the
> __contains__ method actually does something different than this: It
> evaluates the whole QuerySet in bulk at the database level, and starts
> creating model instances ba
Hi,
I created a ticket:
https://code.djangoproject.com/ticket/17156
{{{
The documentation should explain what happens in this code:
if obj in queryset:
If queryset is huge, the above code can be very slow.
If you want to run the code in the database, you should use this:
if queryset
On Wed, Nov 2, 2011 at 10:46 AM, Tom Evans wrote:
> OK, take this example. I have a django model table with 70 million
> rows in it. Doing any kind of query on this table is slow, and
> typically the query is date restrained - which mysql will use as the
> optimum key, meaning any further filteri
On Wed, Nov 2, 2011 at 10:46 AM, Tom Evans wrote:
> On Wed, Nov 2, 2011 at 5:30 PM, Ian Clelland wrote:
> > On Wed, Nov 2, 2011 at 8:25 AM, Thomas Guettler wrote:
> >>
> >> # This is my current solution
> >> if get_special_objects().filter(pk=obj.pk).count():
> >># yes, it is special
> >>
>
Thanks Tom, that's a great explanation!
Furbeenator
On Wed, Nov 2, 2011 at 10:46 AM, Tom Evans wrote:
> On Wed, Nov 2, 2011 at 5:30 PM, Ian Clelland wrote:
> > On Wed, Nov 2, 2011 at 8:25 AM, Thomas Guettler wrote:
> >>
> >> # This is my current solution
> >> if get_special_objects().filter(p
On Wed, Nov 2, 2011 at 5:30 PM, Ian Clelland wrote:
> On Wed, Nov 2, 2011 at 8:25 AM, Thomas Guettler wrote:
>>
>> # This is my current solution
>> if get_special_objects().filter(pk=obj.pk).count():
>> # yes, it is special
>>
>
> I can't speak to the "why" of this situation; it seems to me th
On Wed, Nov 2, 2011 at 8:25 AM, Thomas Guettler wrote:
> # This is my current solution
> if get_special_objects().filter(pk=obj.pk).count():
># yes, it is special
>
>
I can't speak to the "why" of this situation; it seems to me that this
could always be converted into a more efficient databas
On Wed, Nov 2, 2011 at 3:25 PM, Thomas Guettler wrote:
> Here is a better example:
>
> def get_special_objects():
> # Some are special. But the result can still be huge!
> return MyModel.objects.filter()
>
> obj=MyModel.objects.get()
>
> # is this object "special?"
> if obj in get_sp
Here is a better example:
def get_special_objects():
# Some are special. But the result can still be huge!
return MyModel.objects.filter()
obj=MyModel.objects.get()
# is this object "special?"
if obj in get_special_objects(): # This is very slow if there are many rows in
the res
> queryset=MyModel.objects.all()
> obj=MyModel.objects.get(id=319526)
Thomas,
if the second line works for you (i.e. does not raise
MyModel.DoesNotExist exception), then obj is in queryset by
definition.
What are you trying to achieve?
Jirka
--
You received this message because you are
That's because your queryset is being evaluated when you compare, maybe if
you explain your problem, we can give you a better solution than the use of
`in`.
Take a look at the docs about when querysets are evaluated:
https://docs.djangoproject.com/en/dev/ref/models/querysets/#when-querysets-are-e
Hi,
I just discovered, that "if obj in queryset" can be very slow:
queryset=MyModel.objects.all()
obj=MyModel.objects.get(id=319526)
#if obj in queryset: # This is very slow, if queryset is big: All lines from
queryset get created to Python objects
#print 'in'
if queryset.filter(id=obj.id)
12 matches
Mail list logo
