The Python NDB API
Experimental!
NDB is an experimental, innovative, and rapidly changing new feature for App Engine. Unfortunately, being on the bleeding edge means that we may make backwards-incompatible changes to NDB. We will inform the community when this feature is no longer experimental.
The NDB API provides persistent storage in a schemaless object datastore.
It supports automatic caching, sophisticated queries,
and atomic transactions.
NDB is well-suited to storing structured
data records.
It provides an alternative to
the App Engine Datastore API.
NDB has some features that the Datastore API lacks:
- The
StructuredProperty
class,
which allows entities to have nested structure
- Integrated automatic caching, which typically gives fast (and
inexpensive) reads via an in-context cache and Memcache
- Asynchronous APIs which allow concurrent actions (and "synchronous"
APIs if you don't need that)
This reference describes the Python NDB API.
It has the following sections: