id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
31730	manage.py sqlsequencereset not implemented for sqlite3	axil	axil	"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)
}}}"	Bug	assigned	Database layer (models, ORM)	dev	Normal		sql sequence reset sqlite3		Accepted	1	0	0	1	0	0