English majors, feel free to lambast me on my grammar in that last sentence.

The side affect of abstracting the data access layer is that I no longer have to spend much time with database schema. That’s because AppEngine doesn’t run a traditional relational database and doesn’t allow you to run traditional SQL against the data store. I end up writing horribly un-optimized ‘queries’ because I’m not able to write highly optimized SQL queries. The SDK is obviously geared to take full advantage of the instant look up and high throughput that BigTable excels at.

For example, for these 2 objects:

class Attribute(db.Model):
  author = db.UserProperty()
  content = db.StringProperty(multiline=True)
  date = db.DateTimeProperty(auto_now_add=True)

class UserAttribute(db.Model):
  attribute_key = db.ReferenceProperty(Attribute)
  user = db.UserProperty()
  date = db.DateTimeProperty(auto_now_add=True)

I can access all the Attributes that belong to the User with the following code:

    query = db.Query(UserAttribute)
    user_attributes = query.filter('user =', \
      users.get_current_user())
    attributes = [ua.attribute_key for ua in user_attributes]

I’ll keep updating as I dig into the SDK.