ITPEC FE Morning October 2021 Question 28
Which of the following is the main purpose of transaction support in a database management system?
Explanation
All of a transaction's updates are made, or none of them are — transaction support guarantees atomicity.
A transaction groups several updates into one logical unit of work, such as debiting one account and crediting another. If it completes, the DBMS commits all its updates; if it fails midway, the DBMS rolls back the ones already made, so the database is never left half-updated. This is the A of the ACID properties, alongside consistency, isolation and durability.
Answer (a)
Why not others:
- •(b) — limiting access to authorised users is access control, a security function of the DBMS
- •(c) — a graphical interface for updating data is a front-end tool, unrelated to how updates are grouped
- •(d) — a catalog of data item descriptions is the data dictionary, which stores metadata
Key rule: A transaction is all or nothing: commit makes every update permanent together, rollback undoes every update together.
Databases · AI-written, may contain errors
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