Extensible Storage Engine (ESE), an embedded, indexed, and sequential access method (ISAM) database engine, is used in many Microsoft products, including Exchange, Windows Search, and Active Directory. Designed to support applications that have larger indexing or data size requirements and need fast and/or light structured data storage, ESE enables these applications to store and retrieve data from tables using indexed or sequential access. Recently, Microsoft OSS’ed the codebase for ESE, which has been developed internally at Microsoft since 1994. The repository includes reusable sub-facilities, including synchronization and locking library, STL-like data structures library, OS abstraction layer, and block/cache manager.