Add CSM primary key to bigint migration

lms/djangoapps/courseware/migrations/0011_csm_id_bigint.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.23 on 2019-08-28 15:50
+from __future__ import unicode_literals
+
+import courseware.fields
+from django.db import migrations
+from django.db.migrations import AlterField
+
+class CsmBigInt(AlterField):
+    '''
+    Subclass AlterField migration class to split SQL between two different databases
+    We can't use the normal AlterField migration operation because Django generate and routes migrations at the model
+    level and the coursewarehistoryextended_studentmodulehistoryextended table is in a different database
+    '''
+    def database_forwards(self, app_label, schema_editor, from_state, to_state):
+        to_model = to_state.apps.get_model(app_label, self.model_name)
+        if schema_editor.connection.alias == 'student_module_history':
+            schema_editor.execute("ALTER TABLE `coursewarehistoryextended_studentmodulehistoryextended` MODIFY `student_module_id` bigint UNSIGNED NOT NULL;")
+        elif self.allow_migrate_model(schema_editor.connection.alias, to_model):
+            schema_editor.execute("ALTER TABLE `courseware_studentmodule` MODIFY `id` bigint UNSIGNED AUTO_INCREMENT NOT NULL;")
+
+    def database_backwards(self, app_label, schema_editor, from_state, to_state):
+        # Make backwards migration a no-op, app will still work if column is wider than expected
+        pass
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('courseware', '0010_auto_20190709_1559'),
+    ]
+
+    operations = [
+        CsmBigInt(
+            model_name='studentmodule',
+            name='id',
+            field=courseware.fields.UnsignedBigIntAutoField(primary_key=True, serialize=False),
+        )
+    ]

lms/djangoapps/courseware/models.py

@@ -26,6 +26,7 @@ from django.db.models.signals import post_save
 from django.utils.translation import ugettext_lazy as _
 from model_utils.models import TimeStampedModel
 from opaque_keys.edx.django.models import BlockTypeKeyField, CourseKeyField, UsageKeyField
+from courseware.fields import UnsignedBigIntAutoField
 from six import text_type
 from six.moves import range
 
@@ -95,6 +96,8 @@ class StudentModule(models.Model):
                     ('sequential', 'Subsection'),
                     ('library_content', 'Library Content'))
 
+    id = UnsignedBigIntAutoField(primary_key=True)  # pylint: disable=invalid-name
+
     ## These three are the key for the object
     module_type = models.CharField(max_length=32, choices=MODULE_TYPES, default='problem', db_index=True)