11.2. Concurrency and Locking Scenarios
Like many other database systems, DB2 provides support for concurrent data access. While the database is being accessed and manipulated by multiple users, it is important to keep data integrity by using database locking. Before getting into detailed discussions of DB2 locking, you should first understand various concurrent data access scenarios you may encounter and how each DB2 isolation level can prevent these scenarios from occurring or allow these scenarios to occur.
11.2.1. Lost Updates
Assume there is an airline reservation system with multiple agents answering calls for seat reservations. A table called reservations is defined to store flight numbers, seat assignments, and passenger names. Each seat ...