I think mysql used to just give a warning and maybe now it's an error? It
can currently be reproduced with just a blank project (using django master,
mysql 5.5.46-0ubuntu0.14.04.2):
mysql -e'create database mb4test charset utf8mb4'
django-admin startproject mb4test
cd mb4test
vi mb4test/settings.py # set up db settings
./manage.py migrate
Operations to perform:
Apply all migrations: auth, admin, sessions, contenttypes
Running migrations:
Rendering model states... DONE
Applying contenttypes.0001_initial... OK
Applying auth.0001_initial... OK
Applying admin.0001_initial... OK
Applying admin.0002_logentry_remove_auto_add... OK
Applying contenttypes.0002_remove_content_type_name... OK
Applying auth.0002_alter_permission_name_max_length... OK
Applying auth.0003_alter_user_email_max_length... OK
Applying auth.0004_alter_user_username_opts... OK
Applying auth.0005_alter_user_last_login_null... OK
Applying auth.0006_require_contenttypes_0002... OK
Applying auth.0007_alter_validators_add_error_messages... OK
Applying auth.0008_alter_user_username_max_length...Traceback (most
recent call last):
File "/home/collin/django1.10/django/db/backends/utils.py", line 64, in
execute
return self.cursor.execute(sql, params)
File "/home/collin/django1.10/django/db/backends/mysql/base.py", line
112, in execute
return self.cursor.execute(query, args)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
226, in execute
self.errorhandler(self, exc, value)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/connections.py",
line 36, in defaulterrorhandler
raise errorvalue
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
217, in execute
res = self._query(query)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
378, in _query
rowcount = self._do_query(q)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
341, in _do_query
db.query(q)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/connections.py",
line 280, in query
_mysql.connection.query(self, query)
_mysql_exceptions.OperationalError: (1071, 'Specified key was too long; max
key length is 767 bytes')
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "./manage.py", line 10, in <module>
execute_from_command_line(sys.argv)
File "/home/collin/django1.10/django/core/management/__init__.py", line
349, in execute_from_command_line
utility.execute()
File "/home/collin/django1.10/django/core/management/__init__.py", line
341, in execute
self.fetch_command(subcommand).run_from_argv(self.argv)
File "/home/collin/django1.10/django/core/management/base.py", line 290,
in run_from_argv
self.execute(*args, **cmd_options)
File "/home/collin/django1.10/django/core/management/base.py", line 339,
in execute
output = self.handle(*args, **options)
File
"/home/collin/django1.10/django/core/management/commands/migrate.py", line
177, in handle
executor.migrate(targets, plan, fake=fake, fake_initial=fake_initial)
File "/home/collin/django1.10/django/db/migrations/executor.py", line 92,
in migrate
self._migrate_all_forwards(plan, full_plan, fake=fake,
fake_initial=fake_initial)
File "/home/collin/django1.10/django/db/migrations/executor.py", line
121, in _migrate_all_forwards
state = self.apply_migration(state, migration, fake=fake,
fake_initial=fake_initial)
File "/home/collin/django1.10/django/db/migrations/executor.py", line
198, in apply_migration
state = migration.apply(state, schema_editor)
File "/home/collin/django1.10/django/db/migrations/migration.py", line
123, in apply
operation.database_forwards(self.app_label, schema_editor, old_state,
project_state)
File "/home/collin/django1.10/django/db/migrations/operations/fields.py",
line 201, in database_forwards
schema_editor.alter_field(from_model, from_field, to_field)
File "/home/collin/django1.10/django/db/backends/base/schema.py", line
482, in alter_field
old_db_params, new_db_params, strict)
File "/home/collin/django1.10/django/db/backends/base/schema.py", line
634, in _alter_field
params,
File "/home/collin/django1.10/django/db/backends/base/schema.py", line
110, in execute
cursor.execute(sql, params)
File "/home/collin/django1.10/django/db/backends/utils.py", line 79, in
execute
return super(CursorDebugWrapper, self).execute(sql, params)
File "/home/collin/django1.10/django/db/backends/utils.py", line 64, in
execute
return self.cursor.execute(sql, params)
File "/home/collin/django1.10/django/db/utils.py", line 94, in __exit__
six.reraise(dj_exc_type, dj_exc_value, traceback)
File "/home/collin/django1.10/django/utils/six.py", line 685, in reraise
raise value.with_traceback(tb)
File "/home/collin/django1.10/django/db/backends/utils.py", line 64, in
execute
return self.cursor.execute(sql, params)
File "/home/collin/django1.10/django/db/backends/mysql/base.py", line
112, in execute
return self.cursor.execute(query, args)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
226, in execute
self.errorhandler(self, exc, value)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/connections.py",
line 36, in defaulterrorhandler
raise errorvalue
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
217, in execute
res = self._query(query)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
378, in _query
rowcount = self._do_query(q)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/cursors.py", line
341, in _do_query
db.query(q)
File
"/home/collin/mb4test/lib/python3.4/site-packages/MySQLdb/connections.py",
line 280, in query
_mysql.connection.query(self, query)
django.db.utils.OperationalError: (1071, 'Specified key was too long; max
key length is 767 bytes')
On Wed, Dec 30, 2015 at 5:01 AM, Florian Apolloner <[email protected]>
wrote:
>
>
> On Monday, December 21, 2015 at 5:32:43 PM UTC+1, Tim Graham wrote:
>>
>> "This patch breaks on MySQL installations using the utf8mb4 charset,
>> because it breaks the index length limit - it comes out at a maximum of 254
>> * 4 = 1016 bytes whilst by default InnoDB can only index 767 bytes. I found
>> this because I am using utf8mb4 in django-mysql's tests.
>>
>
> Can the original Author of that quote shed more light on "breaking"? To my
> knowledge it just limits the size of the index to the first 767 byte and
> MySQL will give you a warning, so we should be fine, no?
>
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