Atomicity: A transaction is an atomic unit of processing; it is either performed in its entirety or not performed at all. Consistency preservation: A correct execution of the transaction must take …

Hence a transaction, at the simplest level, can be defined as an event involv ing the action of one entity on another. The word ex change is often used to characterize a transaction.

Concurrent execution of user programs is essential for good DBMS performance. Intuitively, the first transaction is transferring $100 from B’s account to A’s account. The second is crediting …

Transaction Concept A transaction is a unit of program execution that accesses and possibly updates various data items. E.g., transaction to transfer $50 from account A to account B: …

Consistency Each transaction takes valid states to valid states: Satisfy integrity constraints Sometimes the only notion of “valid” state is “a state that could have been produced by …

Transaction Processing Concepts Goals: Understand the basic properties of a transaction and learn the concepts underlying transaction processing as well as the concurrent executions of …

In this chapter, we review more closely what we mean by a transaction, we look at the evolution of transaction processing, and we then consider how it differs from other types of information …