See datastore-to-bigquery and datastore-backup for an alternative.

Automates replication from AppEngine to CloudSQL, CloudStorage or S3

• create a CloudSQL instance in the Google API Console, allow your Application to access it. See Getting Started for more Details. We assume it is named mytestinstance
• create a Database inside your instance: CREATE DATABASE test;

Now you can add gaetk_replication to your project:

mkdir -p lib
git submodule add git@github.com:hudora/gaetk_replication.git lib/gaetk_replication
echo "gaetk_replication_SQL_INSTANCE_NAME = 'something:mytestinstance'" >> appengine_config.py
echo "gaetk_replication_SQL_DATABASE_NAME = 'test'" >> appengine_config.py

Adjust names to match your setup.

Now add the replicatior to your app.yaml:

handlers:
- url: /gaetk_replication/.*
  script: replication.cloudsql.application
  login: admin

That's it. Deploy and call /gaetk_replication/cloudsql/cron.