#28459: Improve performance of QuerySet
-------------------------------------+-------------------------------------
Reporter: Sergey Fedoseev | Owner: nobody
Type: | Status: closed
Cleanup/optimization |
Component: Database layer | Version: master
(models, ORM) |
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Accepted
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Sergey Fedoseev):
[https://github.com/django/django/pull/8849 PR (Improved performance of
SQLCompiler.results_iter())]
Before:
{{{
In [3]: %timeit for x in City.objects.values_list('id'): pass
74 ms ± 1.45 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
In [2]: %timeit for x in City.objects.annotate(v=models.Value(1,
output_field=models.IntegerField())).values_list('v'): pass
343 ms ± 2.62 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
}}}
After:
{{{
In [4]: %timeit for x in City.objects.values_list('id'): pass
69.1 ms ± 744 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)
In [3]: %timeit for x in City.objects.annotate(v=models.Value(1,
output_field=models.IntegerField())).values_list('v'): pass
254 ms ± 1.61 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
}}}
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Ticket URL: <https://code.djangoproject.com/ticket/28459#comment:5>
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