Merge pull request #22391 from edx/rename_start_in_schedule_3/5

Rename start in schedule 3/5

openedx/core/djangoapps/schedules/migrations/0009_schedule_copy_column_values.py

@@ -0,0 +1,35 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.26 on 2019-11-24 20:52
+from __future__ import unicode_literals
+
+from django.db import migrations, transaction
+
+
+def copy_column_value_forwards(apps, schema_editor):
+    """
+    Copy the start field into start_date field
+
+    This table has around 25 million rows, we'll follow non-atomic migrations.
+    https://docs.djangoproject.com/en/2.2/howto/writing-migrations/#non-atomic-migrations
+    """
+    Schedule = apps.get_model('schedules', 'Schedule')
+    while Schedule.objects.filter(start_date__isnull=True).exists():
+        with transaction.atomic():
+            for row in Schedule.objects.filter(start_date__isnull=True)[:1000]:
+                row.start_date = row.start
+                row.save()
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ('schedules', '0008_add_new_start_date_field'),
+    ]
+
+    operations = [
+        migrations.RunPython(
+            copy_column_value_forwards,
+            reverse_code=migrations.RunPython.noop,  # Allow reverse migrations, but make it a no-op.
+        )
+    ]