Re: [Django] #29260: Django makes an extra UPDATE query when custom PK is evaluating before save.
#29260: Django makes an extra UPDATE query when custom PK is evaluating before
save.
-+-
Reporter: user0007 |Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 2.0
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0| Needs documentation: 0
Needs tests: 0| Patch needs improvement: 0
Easy pickings: 0|UI/UX: 0
-+-
Comment (by Simon Charette):
> A fix might try to detect if the primary key came from a default and if
so, skip the update.
I think we could use some kind of `self._state.adding and
self._meta.pk.default` heuristics to automatically set `force_insert=True`
on the last table/leaf child. That would break the following scenario
though.
{{{#!python
a = Account(pk='known-uuid-pk')
a.title = new_title
a.save() # expects an UPDATE here.
}}}
But I would argue that `force_update` should be passed in this case.
That wouldn't solve the MTI issue described in #29129 but that would do
for this case.
--
Ticket URL: <https://code.djangoproject.com/ticket/29260#comment:3>
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The Web framework for perfectionists with deadlines.
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Re: [Django] #29260: Django makes an extra UPDATE query when custom PK is evaluating before save.
#29260: Django makes an extra UPDATE query when custom PK is evaluating before save. -+- Reporter: user0007 |Owner: nobody Type: Bug | Status: new Component: Database layer | Version: 2.0 (models, ORM) | Severity: Normal | Resolution: Keywords: | Triage Stage: | Unreviewed Has patch: 0| Needs documentation: 0 Needs tests: 0| Patch needs improvement: 0 Easy pickings: 0|UI/UX: 0 -+- Comment (by Tim Graham): I'm not sure if the issue can or should be fixed. For the model you gave, an instance will have an `id` from `default=uuid.uuid4`, so [https://docs.djangoproject.com/en/stable/ref/models/instances/#how- django-knows-to-update-vs-insert as documented] an `UPDATE` is tried ([https://github.com/django/django/blob/4554f9a783665d64b59c35b53ae71178e56ac783/django/db/models/base.py#L804-L805 code]). A fix might try to detect if the primary key came from a `default` and if so, skip the update. -- Ticket URL: <https://code.djangoproject.com/ticket/29260#comment:2> Django <https://code.djangoproject.com/> The Web framework for perfectionists with deadlines. -- You received this message because you are subscribed to the Google Groups "Django updates" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-updates+unsubscr...@googlegroups.com. To post to this group, send email to django-updates@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-updates/066.fb8ccdaf9d20dc9a4e5bf0cbdc5b6ce2%40djangoproject.com. For more options, visit https://groups.google.com/d/optout.
Re: [Django] #29260: Django makes an extra UPDATE query when custom PK is evaluating before save.
#29260: Django makes an extra UPDATE query when custom PK is evaluating before
save.
-+-
Reporter: user0007 |Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 2.0
(models, ORM) |
Severity: Normal | Resolution:
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0| Needs documentation: 0
Needs tests: 0| Patch needs improvement: 0
Easy pickings: 0|UI/UX: 0
-+-
Description changed by user0007:
Old description:
> Using model's instance:
>
> {{{
>
> class Account(models.Model):
> id = models.UUIDField(
> primary_key=True,
> default=uuid.uuid4,
> editable=False
> )
> title = models.TextField()
>
> >> account = Account()
> >> account.title = "abc"
> >> account.save()
>
> 1. UPDATE "app_account" SET "title" = \'\', WHERE "app_account"."id" =
> \'67c9327d-150e-419f-b493-0c2c59a045c3\'::uuid',
> 2. INSERT INTO "app_account" ("title", "id") VALUES (\'abc\', \'3d8c1b3c-
> 214a-4798-a0fa-d4c22c2b877f\'::uuid)
>
> }}}
>
> Using model's manager method:
>
> {{{
> >> Account.objects.create(title="abc")
>
> 1. INSERT INTO "app_account" ("title", "id") VALUES (\'abc\', \'3d8c1b3c-
> 214a-4798-a0fa-d4c22c2b877f\'::uuid)
> }}}
>
> Related issue? https://code.djangoproject.com/ticket/29129
New description:
Using a model's instance:
{{{
class Account(models.Model):
id = models.UUIDField(
primary_key=True,
default=uuid.uuid4,
editable=False
)
title = models.TextField()
>> account = Account()
>> account.title = "abc"
>> account.save()
1. UPDATE "app_account" SET "title" = \'\', WHERE "app_account"."id" =
\'67c9327d-150e-419f-b493-0c2c59a045c3\'::uuid',
2. INSERT INTO "app_account" ("title", "id") VALUES (\'abc\', \'3d8c1b3c-
214a-4798-a0fa-d4c22c2b877f\'::uuid)
}}}
Using a model's manager method:
{{{
>> Account.objects.create(title="abc")
1. INSERT INTO "app_account" ("title", "id") VALUES (\'abc\', \'3d8c1b3c-
214a-4798-a0fa-d4c22c2b877f\'::uuid)
}}}
Using a model's instance with `force_insert` argument:
{{{
>> account = Account()
>> account.title = "abc"
>> account.save(force_insert=true)
1. INSERT INTO "app_account" ("title", "id") VALUES (\'abc\', \'3d8c1b3c-
214a-4798-a0fa-d4c22c2b877f\'::uuid)
}}}
Related issue? https://code.djangoproject.com/ticket/29129
--
--
Ticket URL: <https://code.djangoproject.com/ticket/29260#comment:1>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
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[Django] #29260: Django makes an extra UPDATE query when custom PK is evaluating before save.
#29260: Django makes an extra UPDATE query when custom PK is evaluating before
save.
-+-
Reporter: user0007 | Owner: nobody
Type: Bug| Status: new
Component: Database |Version: 2.0
layer (models, ORM)|
Severity: Normal | Keywords:
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 |Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
-+-
Using model's instance:
{{{
class Account(models.Model):
id = models.UUIDField(
primary_key=True,
default=uuid.uuid4,
editable=False
)
title = models.TextField()
>> account = Account()
>> account.title = "abc"
>> account.save()
1. UPDATE "app_account" SET "title" = \'\', WHERE "app_account"."id" =
\'67c9327d-150e-419f-b493-0c2c59a045c3\'::uuid',
2. INSERT INTO "app_account" ("title", "id") VALUES (\'abc\', \'3d8c1b3c-
214a-4798-a0fa-d4c22c2b877f\'::uuid)
}}}
Using model's manager method:
{{{
>> Account.objects.create(title="abc")
1. INSERT INTO "app_account" ("title", "id") VALUES (\'abc\', \'3d8c1b3c-
214a-4798-a0fa-d4c22c2b877f\'::uuid)
}}}
Related issue? https://code.djangoproject.com/ticket/29129
--
Ticket URL: <https://code.djangoproject.com/ticket/29260>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
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