The document provides an overview of Doctrine 2, an object-relational mapper (ORM) for PHP. Some key points:
- Doctrine 2 has been completely rewritten from Doctrine 1 and requires PHP 5.3. It uses namespaces, has a new architecture and workflow.
- It provides a database abstraction layer (DBAL), object relational mapper (ORM), and common utilities. The DBAL can be used independently of the ORM.
- Entities do not need to extend a base class. Metadata is provided via annotations, YAML or XML.
- Performance is improved over Doctrine 1 through optimizations like a faster hydration algorithm.
- The documentation covers