get_table_list in postgresql introspection is unordered

[Claude Paroz]

After looking for the cause of test failures after r17942, I realized that get_table_list result ordering is not consistent between backends.

The list is explicitely ordered by table name in sqlite3, implicitely ordered (SHOW TABLES) in MySQL, and unordered in PostgreSQL and Oracle.

I suggest to fix this by ordering by table name in PostgreSQL and Oracle and adding a test case.

[Anssi Kääriäinen]

Seems like a good idea to me. This would result in the models created in alphabetical order, too?

[Claude Paroz]

Sort table names in get_table_list

[Claude Paroz]

This would result in sorted models by table name in inspectdb, at least. Models creation order is probably another story, but indirectly, the former might influence the latter. Of course, the user is free to reorder models in inspectdb result before feeding it to the database.

[Anssi Kääriäinen]

The patch does not work correctly on my Oracle setup. I get this error:

Traceback (most recent call last):
  File "/home/akaariai/Programming/django/tests/regressiontests/introspection/tests.py", line 25, in _inner
    return func(*args, **kwargs)
  File "/home/akaariai/Programming/django/tests/regressiontests/introspection/tests.py", line 43, in test_table_names
    self.assertEqual(tl, sorted(tl))
AssertionError: Lists differ: [u'auth_group', u'auth_group_p... != [u'auth_group', u'auth_group_p...

First differing element 7:
django_comments
django_comment_flags

  [u'auth_group',
   u'auth_group_permissions',
   u'auth_permission',
   u'auth_user',
   u'auth_user_groups',
   u'auth_user_user_permissions',
   u'django_admin_log',
+  u'django_comment_flags',
   u'django_comments',
-  u'django_comment_flags',
   u'django_content_type',
   u'django_flatpage',
   u'django_flatpage_sites',
   u'django_ixn_test_table',
   u'django_redirect',
   u'django_session',
   u'django_site',
   u'inspectdb_digitsincolumnname',
   u'inspectdb_message',
   u'inspectdb_people',
   u'inspectdb_peopledata',
   u'inspectdb_peoplemoredata',
   u'introspection_article',
   u'introspection_reporter']

The reason for the error seems to be that Oracle sorts '_' and 's' characters differently than Python. In general the sort order of the database might be different than the sort order of Python. A good enough fix for this case is to check just one pair of tables, hopefully a pair which is incorrectly sorted without the patch, but correctly sorted with the patch.

There are a couple of other Oracle tests failing already, but adding more isn't a good way forward.

BTW In comment:1 I meant to say that the model order created by inspectdb is altered (a positive side-effect), not that model creation order is altered. I managed to write the wrong thing there...

[Anssi Kääriäinen]

I went the easy route and just made introspection.table_names() return sorted() table names. This avoids the use of the Database's ORDER BY. I also reordered the introspection methods & usage a little, that is get_table_list() is never used directly outside of backends, always use table_names() instead.

See ​https://github.com/django/django/pull/16

[Adrian Holovaty]

Merged.