#35246: Make Field.unique a plain attribute
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Owner: Adam
Type: | Johnson
Cleanup/optimization | Status: assigned
Component: Database layer | Version: dev
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by Adam Johnson:
Old description:
> Another candidate for caching, like #35230, #35232 and #35241, following
> the same system check profiling.
>
> `Field.unique` is a simple property that computes whether a field is
> unique from two inputs:
>
> {{{
> @property
> def unique(self):
> return self._unique or self.primary_key
> }}}
>
> The result is immutable because the two input attributes shouldn’t
> change.
>
> I found this method was called 3543 times during system checks, taking
> ~0.7% (~0.3ms) of the total runtime on a Python 3.12 project with 118
> models. After moving it to a plain attribute, this cost is eliminated.
> (cProfile’s overhead biases the cost of function calls upwards, so the
> actual saving may be smaller, but it still seems worth the minimal
> change.)
>
> `unique` is accessed in many other code paths so this change will help
> those paths too.
New description:
Another candidate for caching, like #35230, #35232 and #35241, following
the same system check profiling.
`Field.unique` is a simple property that computes whether a field is
unique from two inputs:
{{{
@property
def unique(self):
return self._unique or self.primary_key
}}}
The result is immutable because the two input attributes shouldn’t change.
I found this method was called 3543 times during system checks, taking
~0.7% (~0.3ms) of the total runtime on a Python 3.12 project with 118
models. After moving it to a plain attribute, this cost is eliminated.
(cProfile’s overhead biases the cost of function calls upwards, so the
actual saving may be smaller, but it still seems worth the minimal
change.)
`unique` is accessed in many other code paths so this change will help
those paths too.
--
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Ticket URL: <https://code.djangoproject.com/ticket/35246#comment:2>
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