Computer Science – 8.2 Database Management Systems (DBMS) | e-Consult

A transaction management system within a DBMS is responsible for ensuring that database operations are performed reliably and consistently. It guarantees that a series of operations are treated as a single, indivisible unit of work – a transaction. This is achieved through the enforcement of the ACID properties:

• Atomicity: All operations within a transaction must succeed or fail as a whole. If any operation fails, the entire transaction is rolled back, leaving the database in its original state.
• Consistency: A transaction must transform the database from one valid state to another valid state. It ensures that all defined constraints and rules are maintained.
• Isolation: Transactions are isolated from each other. Concurrent transactions do not interfere with each other's operations. This prevents issues like dirty reads, non-repeatable reads, and phantom reads.
• Durability: Once a transaction is committed, the changes are permanent and will survive even system failures (e.g., power outages).

Transaction management is crucial in scenarios where data integrity is paramount. For example, consider an online banking system where a user transfers money from one account to another. This involves two operations: debiting the source account and crediting the destination account. If the debit operation succeeds but the credit operation fails (due to a system error), the money would be lost. Transaction management ensures that either both operations succeed (atomicity and consistency) or both are rolled back, preventing data loss and maintaining the integrity of the banking system. Without transaction management, the database could become inconsistent and unreliable.