Berkeley DB also provides core database services to developers. These -services include:

+ Berkeley DB also provides core database services to + developers. These services include: +

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Page cache management:: The page cache provides fast access to a cache of database pages, -handling the I/O associated with the cache to ensure that dirty pages -are written back to the file system and that new pages are allocated on -demand. Applications may use the Berkeley DB shared memory buffer manager to -serve their own files and pages.; + The page cache provides fast access to a cache + of database pages, handling the I/O associated with + the cache to ensure that dirty pages are written back + to the file system and that new pages are allocated on + demand. Applications may use the Berkeley DB shared + memory buffer manager to serve their own files and + pages. +
Transactions and logging:: The transaction and logging systems provide recoverability and atomicity -for multiple database operations. The transaction system uses two-phase -locking and write-ahead logging protocols to ensure that database -operations may be undone or redone in the case of application or system -failure. Applications may use Berkeley DB transaction and logging subsystems -to protect their own data structures and operations from application or -system failure.; + The transaction and logging systems provide + recoverability and atomicity for multiple database + operations. The transaction system uses two-phase + locking and write-ahead logging protocols to ensure + that database operations may be undone or redone in + the case of application or system failure. + Applications may use Berkeley DB transaction and + logging subsystems to protect their own data + structures and operations from application or system + failure. +
Locking:: The locking system provides multiple reader or single writer access to -objects. The Berkeley DB access methods use the locking system to acquire -the right to read or write database pages. Applications may use the -Berkeley DB locking subsystem to support their own locking needs.; + The locking system provides multiple reader or + single writer access to objects. The Berkeley DB + access methods use the locking system to acquire the + right to read or write database pages. Applications + may use the Berkeley DB locking subsystem to support + their own locking needs. +

By combining the page cache, transaction, locking, and logging systems, -Berkeley DB provides the same services found in much larger, more complex and -more expensive database systems. Berkeley DB supports multiple simultaneous -readers and writers and guarantees that all changes are recoverable, even -in the case of a catastrophic hardware failure during a database update.

Developers may select some or all of the core database services for any -access method or database. Therefore, it is possible to choose the -appropriate storage structure and the right degrees of concurrency and -recoverability for any application. In addition, some of the subsystems -(for example, the Locking subsystem) can be called separately from the -Berkeley DB access method. As a result, developers can integrate non-database -objects into their transactional applications using Berkeley DB.

+ By combining the page cache, transaction, locking, and + logging systems, Berkeley DB provides the same services found + in much larger, more complex and more expensive database + systems. Berkeley DB supports multiple simultaneous readers + and writers and guarantees that all changes are recoverable, + even in the case of a catastrophic hardware failure during a + database update. +

+ Developers may select some or all of the core database + services for any access method or database. Therefore, it is + possible to choose the appropriate storage structure and the + right degrees of concurrency and recoverability for any + application. In addition, some of the subsystems (for example, + the Locking subsystem) can be called separately from the + Berkeley DB access method. As a result, developers can + integrate non-database objects into their transactional + applications using Berkeley DB. +