#32244: ORM inefficiency: ModelFormSet executes a single-object SELECT query per
formset instance when saving/validating
-------------------------------------+-------------------------------------
Reporter: Lushen Wu | Owner: nobody
Type: | Status: closed
Cleanup/optimization |
Component: Database layer | Version: 3.1
(models, ORM) |
Severity: Normal | Resolution: wontfix
Keywords: formsets | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Carlton Gibson):
* status: new => closed
* resolution: => wontfix
Comment:
Hi. Thanks for the report.
It looks like you'e dug into the various aspects.
This seems to make the most sense to me:
> The easiest solution seems to me to pass BaseModelFormSet._object_dict
in some way to each ModelForm that's created, and then allow the
ModelChoiceField to check this _object_dict before making another SELECT
query.
You'd pass a reference via the form kwargs, and then need a custom form
and `ModelChoiceField` subclass to make use of it in `to_python()`.
I have to say this is probably a `wontfix`. It's not likely that this is a
performance bottleneck for most projects. Even several hundred lookups are
not going to noticeably affect the form submission in normal cases.
Projects needing to process data in a performant tight-loop will want to
make adjustments as discusses here, but the complication there probably
isn't worth it for the general case.
If you experiment in your own project and come up with a clean and simple
solution, it may be worth reviewing then, either here or on the
DevelopersMailingList.
I hope that makes sense.
Thanks.
--
Ticket URL: <https://code.djangoproject.com/ticket/32244#comment:7>
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