ObjectStore is an object-oriented database management system (OODBMS) that provides a tightly integrated language interface to the traditional database management system (DBMS) features of persistent storage, transaction management, distributed data access, and associative queries. ObjectStore was designed for use in applications that perform complex manipulations on large databases of objects with intricate structure. Developers of these applications require high productivity through ease of use, expressive power, a reusable code base, and tight integration with the host environment. Even more important is the need for high performance. Speed cannot be sacrificed to obtain these benefits. The key to meeting these requirements is the virtual memory-mapping architecture. ObjectStore's collection, relationship, and query facilities provide support for conceptual modeling constructs, such as multivalued attributes, and many-to-many relationships can be translated directly into declarative ObjectStore constructs.