ITPEC FE Morning April 2018 Question 26
ITPEC FE Morning April 2018 — Question 26 of 80
ACID — Durability — recover committed data after system/storage failure.
ACID properties of database transactions:
- •Atomicity — all-or-nothing: transaction fully completes or fully rolls back
- •Consistency — database moves from one valid state to another
- •Isolation — concurrent transactions don't interfere with each other
- •Durability — once committed, data survives system or storage failure
Why Durability:
The question says "recover a committed transaction when system or storage media fails" — this is the definition of Durability.
Why not others:
- (a) Atomicity — about all-or-nothing execution, not crash recovery
- (b) Consistency — about maintaining valid database state, not failure recovery
- (d) Isolation — about separating concurrent transactions, not persistence after failure
Key rule: Durability = committed data is permanent, even if hardware crashes.
AI-generated — may contain errors
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