For the past couple of weeks, I've been working on one of those projects that seems to suck up every available moment (and some that technically aren't). Now, however, it's largely done, and as an extra bonus, I've been given permission to release it as an early preview for those that are interested.
The code in question is a new implementation of the local datastore for the Python App Engine SDK. While some of you are probably delighted at the news, I expect most of you are puzzled. Why do we need a new local datastore implementation? Let me explain.
The purpose of the local stubs in the App Engine SDK is to exactly replicate the behaviour of the production environment, and in general they do that very well. A specific non-goal is replicating the performance characteristics of the production environment, or being as scalable as the production environment - the stubs are designed for testing, not production use.
The Python SDK's datastore implementation operates by storing the entire contents of your development datastore in memory. It writes changes to disk so that it can reload your datastore when the dev_appserver is restarted, but the in-memory ...