Re: QuerySet: "if obj in queryset" can be very slow

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 >

Re: QuerySet: "if obj in queryset" can be very slow

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

Re: QuerySet: "if obj in queryset" can be very slow

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,

Re: QuerySet: "if obj in queryset" can be very slow

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

Re: QuerySet: "if obj in queryset" can be very slow

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: > >> > >> #

Re: QuerySet: "if obj in queryset" can be very slow

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

Re: QuerySet: "if obj in queryset" can be very slow

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

Re: QuerySet: "if obj in queryset" can be very slow

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

Re: QuerySet: "if obj in queryset" can be very slow

lazy. I have no big problem with this, since I found a solution. Is there a reason why "if obj in queryset" is executed in python code, and not in the DB? Thomas Am 02.11.2011 12:42, schrieb Thomas Guettler: > Hi, > > I just discovered, that "if obj in queryset" ca

Re: QuerySet: "if obj in queryset" can be very slow

> 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

Re: QuerySet: "if obj in queryset" can be very slow

-are-evaluated []'s On Wed, Nov 2, 2011 at 9:42 AM, Thomas Guettler <h...@tbz-pariv.de> wrote: > 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 qu

QuerySet: "if obj in queryset" can be very slow

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