bug fixes and support several features for django migrations

CHANGES.rst

@@ -9,16 +9,46 @@ General:
 * #87 Drop py2 wheel tag from release package file.
 * Add `CODE_OF_CONDUCT.rst` The linked text which has been referred to from CONTRIBUTING.rst is now included.
 
+Incompatible Changes:
+
+* #97 To specify SORTKEY for Redshift, you must use `django_redshift_backend.SortKey` for
+  `Model.Meta.ordering` instead of bearer string.
+
+  **IMPORTANT**:
+  With this change, existing migration files that specify ordering are not affected.
+  If you want to apply SortKey to your migration files, please comment out the ordering option once and run
+  makemigrations, then comment in the ordering option and run makemigrations again.
+
+* #97 `django_redshift_backend.distkey.DistKey` is moved to `django_redshift_backend.DistKey`.
+  However old name is still supported for a compatibility.
+
+* #97 Now django-redshift-backend doesn't support `can_rollback_ddl`.
+  Originally, Redshift did not support column name/type(size) changes within a transaction.
+  Please refer https://github.com/jazzband/django-redshift-backend/issues/96
+
+* #97 changed the behavior of implicit not null column addition.
+  previously, adding a not null column was implicitly changed to allow null.
+  now adding not null without default raises a programmingerror exception.
 
 Bug Fixes:
 
 * #92, #93: since django-3.0 sqlmigrate (and migrate) does not work.
-* #90, #13: fix database inspection capability with `manage.py inspectdb`. Thanks to Matt Fisher.
+* #37: fix Django `contenttype` migration that cause `ProgrammingError: cannot drop sortkey column
+  "name"` exception.
+* #64: fix Django `auth` migration that cause `NotSupportedError: column "content_type__app_label"
+  specified as distkey/sortkey is not in the table "auth_permission"` exception.
 
 Features:
 
 * #82 Add Python-3.10 support.
 * #82 Drop Django-3.0 support.
+* #90, #13: Support `manage.py inspectdb`, also support working with the django-sql-explorer package.
+  Thanks to Matt Fisher.
+* #63 Support changing a field from NOT NULL to NULL on migrate / sqlmigrate.
+* #97 Support VARCHAR size changing for UNIQUE, PRIMARY KEY, FOREIGN KEY.
+* #97 Support backward migration for DROP NOT NULL column wituout DEFAULT.
+  One limitation is that the DEFAULT value is set to match the type. This is because the only way for
+  Redshift to add NOT NULL without default is to recreate the table.
 
 2.1.0 (2021/09/23)
 ------------------

django_redshift_backend/__init__.py

@@ -12,3 +12,5 @@
     except DistributionNotFound:
         # package is not installed
         pass
+
+from django_redshift_backend.meta import DistKey, SortKey  # noqa

django_redshift_backend/distkey.py

@@ -1,17 +1,3 @@
-from __future__ import absolute_import
-
-from django.db.models import Index
-
-
-class DistKey(Index):
-    """A single-field index denoting the distkey for a model.
-
-    Use as follows:
-
-      class MyModel(models.Model):
-      ...
-
-      class Meta:
-          indexes = [DistKey(fields=['customer_id'])]
-    """
-    pass
+# flake8: noqa
+# for backward compatibility before 3.0.0
+from .meta import DistKey

django_redshift_backend/meta.py

@@ -0,0 +1,45 @@
+from django.db.models import Index
+
+
+class DistKey(Index):
+    """A single-field index denoting the distkey for a model.
+
+    Use as follows:
+
+      class MyModel(models.Model):
+      ...
+
+      class Meta:
+          indexes = [DistKey(fields=['customer_id'])]
+    """
+    def deconstruct(self):
+        path, expressions, kwargs = super().deconstruct()
+        path = path.replace('django_redshift_backend.meta', 'django_redshift_backend')
+        return (path, expressions, kwargs)
+
+
+class SortKey(str):
+    """A SORTKEY in Redshift, also valid as ordering in Django.
+
+    https://docs.djangoproject.com/en/dev/ref/models/options/#django.db.models.Options.ordering
+
+    Use as follows:
+
+      class MyModel(models.Model):
+      ...
+
+      class Meta:
+          ordering = [SortKey('created_at'), SortKey('-id')]
+    """
+    def __hash__(self):
+        return hash(str(self))
+
+    def deconstruct(self):
+        path = '%s.%s' % (self.__class__.__module__, self.__class__.__name__)
+        path = path.replace('django_redshift_backend.meta', 'django_redshift_backend')
+        return (path, [str(self)], {})
+
+    def __eq__(self, other):
+        if self.__class__ == other.__class__:
+            return self.deconstruct() == other.deconstruct()
+        return NotImplemented

doc/refs.rst

@@ -92,21 +92,24 @@ Django Models
 Using sortkey
 -------------
 
-There is built-in support for this option for Django >= 1.9. To use `sortkey`, simply define an `ordering` on the model meta as follow::
+There is built-in support for this option for Django >= 1.9. To use `sortkey`, define an `ordering` on the model
+meta with the custom sortkey type `django_redshift_backend.SortKey` as follow::
 
   class MyModel(models.Model):
       ...
 
       class Meta:
-          ordering = ['col2']
+          ordering = [SortKey('col2')]
+
+`SortKey` in `ordering` are also valid as ordering in Django.
 
 N.B.: there is no validation of this option, instead we let Redshift validate it for you. Be sure to refer to the `documentation <http://docs.aws.amazon.com/redshift/latest/dg/r_CREATE_TABLE_examples.html>`_.
 
 Using distkey
 -------------
 
 There is built-in support for this option for Django >= 1.11. To use `distkey`, define an index on the model
-meta with the custom index type `django_redshift_backend.distkey.DistKey` with `fields` naming a single field::
+meta with the custom index type `django_redshift_backend.DistKey` with `fields` naming a single field::
 
   class MyModel(models.Model):
       ...
@@ -143,7 +146,7 @@ That is, to go from::
        ...
        migrations.AddIndex(
             model_name='facttable',
-            index=django_redshift_backend.distkey.DistKey(fields=['distkeycol'], name='...'),
+            index=django_redshift_backend.DistKey(fields=['distkeycol'], name='...'),
         ),
     ]
 
@@ -160,7 +163,7 @@ To::
                 ...
             ],
             options={
-                'indexes': [django_redshift_backend.distkey.DistKey(fields=['distkeycol'], name='...')],
+                'indexes': [django_redshift_backend.DistKey(fields=['distkeycol'], name='...')],
             },
         ),
        ...

examples/proj1/testapp/models.py

@@ -2,7 +2,7 @@
 
 from django.db import models
 
-from django_redshift_backend.base import DistKey
+from django_redshift_backend.base import DistKey, SortKey
 
 
 class TestModel(models.Model):
@@ -23,7 +23,7 @@ class TestModelWithMetaKeys(models.Model):
 
     class Meta:
         indexes = [DistKey(fields=['fk'])]
-        ordering = ['created_at', '-id']
+        ordering = [SortKey('created_at'), SortKey('-id')]
 
 
 class TestParentModel(models.Model):