fix!: Update the migration to have one Index on student_module_id

This updates the migration to have one index on student_module_id. Previously we had one index on stage and production of edx.org but two indexes on other envs. This change is to make sure we have one index on every env. But this change drops the index and create a new index, so if you have set ENABLE_CSMH_EXTENDED to True and have coursewarehistoryextended_studentmodulehistoryextended in a separate db and you want to avoid rebuilding the index, you can fake this migration.

Author: iamsobanjaved

lms/djangoapps/coursewarehistoryextended/migrations/0003_rename_studentmodulehistoryextended_student_module_student_module_idx.py

@@ -1,6 +1,7 @@
 # Generated by Django 4.2.20 on 2025-05-15 03:30
 
-from django.db import migrations
+from django.db import migrations, models
+import django.db.models.deletion
 
 
 class Migration(migrations.Migration):
@@ -10,9 +11,26 @@ class Migration(migrations.Migration):
     ]
 
     operations = [
-        migrations.RenameIndex(
+        migrations.AlterField(
             model_name='studentmodulehistoryextended',
-            new_name='student_module_idx',
-            old_fields=('student_module',),
+            name='student_module',
+            field=models.ForeignKey(db_constraint=False, db_index=False, on_delete=django.db.models.deletion.DO_NOTHING, to='courseware.studentmodule'),
+        ),
+        # This SeparateDatabaseAndState operation updates the state to match the model.
+        # database_operations is left empty because the indexes were already dropped
+        # by the previous operation in the database.
+        migrations.SeparateDatabaseAndState(
+            database_operations=[],
+            state_operations=[
+                migrations.AlterIndexTogether(
+                    name='studentmodulehistoryextended',
+                    index_together=set(),
+                ),
+            ],
+        ),
+        # Adds back the index on 'student_module' to ensure there is a single index on this field.
+        migrations.AddIndex(
+            model_name='studentmodulehistoryextended',
+            index=models.Index(fields=['student_module'], name='student_module_idx'),
         ),
     ]

lms/djangoapps/coursewarehistoryextended/models.py

@@ -42,7 +42,7 @@ class Meta:
 
     id = UnsignedBigIntAutoField(primary_key=True)  # pylint: disable=invalid-name
 
-    student_module = models.ForeignKey(StudentModule, db_index=True, db_constraint=False, on_delete=models.DO_NOTHING)
+    student_module = models.ForeignKey(StudentModule, db_index=False, db_constraint=False, on_delete=models.DO_NOTHING)
 
     @receiver(post_save, sender=StudentModule)
     def save_history(sender, instance, **kwargs):  # pylint: disable=no-self-argument, unused-argument