The GATE Grind

GATE 2016 CS (CS2) – Question 61

Databases · Transactions and Concurrency Control · 2 marks · Multiple choice

S = r₂(X); r₁(X); r₂(Y); w₁(X); r₁(Y); w₂(X); a₁; a₂, where r,w mean read/write and a means abort. Which statement is true?

  1. S is nonrecoverable
  2. S is recoverable but has a cascading abort
  3. S has no cascading abort
  4. S is strict

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Correct answer: (C) S has no cascading abort

Explanation

Every read sees a value from before these transactions’ writes, so there is no dirty-read dependency. Neither abort forces the other through a read-from relationship: no cascading abort occurs, C. The overwrite w₂(X) follows uncommitted w₁(X), so the schedule is not strict.

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