Django makes an extra UPDATE query when custom PK is evaluating before save.

[user0007]

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