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:

• NDB Overview
• Entities and Keys
• Properties
• Writing Property Subclasses
• Queries
• Transactions
• Administration
• Asynchronous Operation
• Caching
• Reference
  • Context
  • Future
  • Key
  • Model
  • Query
  • PolyModel
  • Metadata
  • functions