On Tue, 2020-06-02 at 11:31 -0700, Javier Buzzi wrote:
> ps @roger
>
> >>> timeit.timeit('m.GL.objects.filter(pk=x.pk)', setup='import
> myapp.models as m;x = m.GL.objects.all()[324]', number=100)
> 0.05818330496549606
>
> is not doing anything, add a `.exists()` or `len(..)` or something to
> evaluate the queryset. That number is WAY too low.
Yes, of course. That makes me feel silly, on both counts - the
evaluations and the number of iterations. I made number of iterations
low;because I started with a test which a single iteration was taking
multiple seconds and it that case the default number was way to high
for the quick test I was offering. More critically the x in qs; depends
on where in the qs the object is and it doesn't matter how big if you
only look at the beginning.
I reran it; but which shows different results.. See the following re
run. Construction here is more complicated to show avg microsecs; per
iteration, note the vary iteration lengths, actual runtime was aimed to
be between 20secs and a minute or so.
>>> # Searching for first in queryset>>> n=10_000_000 ;timeit.timeit('x
in qs', setup='import myapp.models as m;qs = m.GL.objects.all();
qs2=qs;i=len(qs2);x=qs[0]',
number=n)/(n/1_000_000)0.4136358265765011>>> n = 100_000 ;
timeit.timeit('m.GL.objects.filter(pk=x.pk)', setup='import
myapp.models as m;x =
list(m.GL.objects.all())[0]', number=n)/(n/1_000_000)124.9944525491446
3>>> # Searching for last in queryset.>>> n=1000; timeit.timeit('x in
qs', setup='import myapp.models as m;qs = m.GL.objects.all();
qs2=qs;i=len(qs2);x=qs[i-1]',
number=n)/(n/1_000_000)50741.098549216986>>> n = 100_000 ;
timeit.timeit('m.GL.objects.filter(pk=x.pk)', setup='import
myapp.models as m;x = list(m.GL.objects.all())[-
1]', number=n)/(n/1_000_000)118.99649207945913
--
Roger Gammans <[email protected]>
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