#31730: manage.py sqlsequencereset not implemented for sqlite3
-------------------------------------+-------------------------------------
Reporter: axil | Owner: nobody
Type: Bug | Status: new
Component: Database layer | Version: 3.0
(models, ORM) |
Severity: Normal | Resolution:
Keywords: sql sequence reset | Triage Stage:
sqlite3 | Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Description changed by axil:
Old description:
> Currently `./manage.py sqlsequencereset`
> ([https://docs.djangoproject.com/en/3.0/ref/django-
> admin/#sqlsequencereset docs]) never prints anything for the sqlite3
> backend.
>
> It happens because the function `sequence_reset_sql` defined in
> `django/django/db/backends/base/operations.py`
> is not implemented for the sqlite3 backend in
> `django/django/db/backends/sqlite3/operations.py`
>
> `django/django/contrib/sites/management.py` makes use of this function
>
> {{{
> # We set an explicit pk instead of relying on auto-incrementation,
> # so we need to reset the database sequence. See #17415.
> sequence_sql = connections[using].ops.sequence_reset_sql(no_style(),
> [Site])
> if sequence_sql:
> if verbosity >= 2:
> print("Resetting sequence")
> }}}
>
> Here `sequence_reset_sql` also does nothing for sqlite3, but sqlite3 is
> pretty lenient to
> the sequences, so it didn't result in an exception.
>
> Same applies to its usage in `manage.py loaddata`: sqlite3 fixes the
> sequences automatically.
>
> What it cannot do automatically is reset the sequence to zero as
> demonstrated in the new test
> `django/tests/backends/tests.py:SequenceResetTest.test_reset_sequence`
>
> {{{
> def test_reset_sequence(self):
> Post.objects.create(name='1st post', text='hello world')
>
> Post.objects.all().delete()
>
> # Reset the sequences for the database
> commands =
> connections[DEFAULT_DB_ALIAS].ops.sequence_reset_sql(no_style(), [Post])
> with connection.cursor() as cursor:
> for sql in commands:
> cursor.execute(sql)
>
> # If we create a new object now, it should have a PK greater
> # than the PK we specified manually.
> obj = Post.objects.create(name='New post', text='goodbye world')
> self.assertEqual(obj.pk, 1)
> }}}
New description:
Currently `./manage.py sqlsequencereset`
([https://docs.djangoproject.com/en/3.0/ref/django-admin/#sqlsequencereset
docs]) never prints anything for the sqlite3 backend.
It happens because the function `sequence_reset_sql` defined in
`django/django/db/backends/base/operations.py`
is not implemented for the sqlite3 backend in
`django/django/db/backends/sqlite3/operations.py`
`django/django/contrib/sites/management.py` makes use of this function
{{{
# We set an explicit pk instead of relying on auto-incrementation,
# so we need to reset the database sequence. See #17415.
sequence_sql = connections[using].ops.sequence_reset_sql(no_style(),
[Site])
if sequence_sql:
if verbosity >= 2:
print("Resetting sequence")
}}}
Here `sequence_reset_sql` also does nothing for sqlite3, but sqlite3 is
pretty lenient to
the sequences, so it didn't result in an exception.
Same applies to its usage in `manage.py loaddata`: sqlite3 fixes the
sequences automatically.
Leniency of sqlite is also the explanation of how
`django/tests/backends/tests.py:SequenceResetTest.test_generic_relation`
test contrives to pass with `sequence_reset_sql` being noop for sqlite3.
What it cannot do automatically is reset the sequence to zero as
demonstrated in the new test
`django/tests/backends/tests.py:SequenceResetTest.test_reset_sequence`
{{{
def test_reset_sequence(self):
Post.objects.create(name='1st post', text='hello world')
Post.objects.all().delete()
# Reset the sequences for the database
commands =
connections[DEFAULT_DB_ALIAS].ops.sequence_reset_sql(no_style(), [Post])
with connection.cursor() as cursor:
for sql in commands:
cursor.execute(sql)
# If we create a new object now, it should have a PK greater
# than the PK we specified manually.
obj = Post.objects.create(name='New post', text='goodbye world')
self.assertEqual(obj.pk, 1)
}}}
--
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Ticket URL: <https://code.djangoproject.com/ticket/31730#comment:3>
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