A Level Computer Science OCR Practice Exam

What does the ACID acronym stand for concerning database transactions?

1. Atomicity, Concurrency, Integrity, Data

2. Atomicity, Capacity, Isolation, Durability

3. Atomicity, Consistency, Isolation, Durability

4. Action, Consistency, Isolation, Dependency

The correct answer is: Atomicity, Consistency, Isolation, Durability

The ACID acronym in the context of database transactions stands for Atomicity, Consistency, Isolation, and Durability. Each of these principles plays a critical role in ensuring reliable processing of database transactions. Atomicity ensures that a transaction is treated as a single, indivisible unit. Either all of the operations in the transaction are executed successfully, or none are applied at all. This property helps in maintaining the integrity of the database by preventing partial transactions. Consistency guarantees that a transaction will bring the database from one valid state to another, ensuring that all data integrity constraints are satisfied. If a transaction violates a data constraint, it won’t be committed, thus preserving the consistency of the database. Isolation ensures that concurrent transactions do not interfere with each other. This property allows transactions to execute independently and transparently, as if they are the only transactions in the system, which is crucial for multi-user database applications. Durability ensures that once a transaction has been committed, it will remain so, even in the event of a power loss, crash, or error. This means that the changes made by a committed transaction are permanent and can be recovered. Understanding these core principles helps in designing robust and reliable database systems that can handle transactions safely and efficiently.