populate historic notification postage data

sets all letters in notification history (and notifications) to
"second", so that there's no null letters for billing etc. Commits in
ten day chunks (up to ~30k letters)

app/commands.py

@@ -602,3 +602,49 @@ def bulk_invite_user_to_service(file_name, service_id, user_id, auth_type, permi
                 print("*** ERROR occurred for email address: {}. \n{}".format(email_address.strip(), e))
 
     file.close()
+
+
+@notify_command(name='populate-notification-postage')
+@click.option(
+    '-s',
+    '--start_date',
+    default=datetime(2017, 2, 1),
+    help="start date inclusive",
+    type=click_dt(format='%Y-%m-%d')
+)
+@statsd(namespace="tasks")
+def populate_notification_postage(start_date):
+    current_app.logger.info('populating historical notification postage')
+
+    total_updated = 0
+
+    while start_date < datetime.utcnow():
+        # process in ten day chunks
+        end_date = start_date + timedelta(days=10)
+
+        sql = \
+            """
+            UPDATE {}
+            SET postage = 'second'
+            WHERE notification_type = 'letter' AND
+            postage IS NULL AND
+            created_at BETWEEN :start AND :end
+            """
+
+        execution_start = datetime.utcnow()
+
+        if end_date > datetime.utcnow() - timedelta(days=8):
+            print('Updating notifications table as well')
+            db.session.execute(sql.format('notifications'), {'start': start_date, 'end': end_date})
+
+        result = db.session.execute(sql.format('notification_history'), {'start': start_date, 'end': end_date})
+        db.session.commit()
+
+        current_app.logger.info('notification postage took {}ms. Migrated {} rows for {} to {}'.format(
+            datetime.utcnow() - execution_start, result.rowcount, start_date, end_date))
+
+        start_date += timedelta(days=10)
+
+        total_updated += result.rowcount
+
+    current_app.logger.info('Total inserted/updated records = {}'.format(total_updated))