Implementation of Atomicity and Durability The recovery-management component of a database system implements the support for atomicity and durability The shadow-database scheme x assume that only one transaction is active at a time x a pointer called db_ pointer always points to the current consistent copy of the database t all updates are made on a shadow copy of the database, and db_ pointer is made to point to the updated shadow copy only after the transaction reaches partial commit and all updated pages have been flushed to disk x in case transaction fails, old consistent copy pointed to by db_pointer can be used, and the shadow copy can be deleted 标 Database System Concepts 15.8 OSilberschatz. Korth and SudarshanDatabase System Concepts 15.8 ©Silberschatz, Korth and Sudarshan Implementation of Atomicity and Durability The recovery-management component of a database system implements the support for atomicity and durability. The shadow-database scheme:  assume that only one transaction is active at a time.  a pointer called db_pointer always points to the current consistent copy of the database.  all updates are made on a shadow copy of the database, and db_pointer is made to point to the updated shadow copy only after the transaction reaches partial commit and all updated pages have been flushed to disk.  in case transaction fails, old consistent copy pointed to by db_pointer can be used, and the shadow copy can be deleted