Multiple choice

Which of the following scenarios may lead to an irrecoverable error in a database system?

  1. A transaction writes a data item after it is read by an uncommitted transaction.

  2. A transaction reads a data item after it is read by an uncommitted transaction.

  3. A transaction reads a data item after it is written by a committed transaction.

  4. A transaction reads a data item after it is written by an uncommitted transaction.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Option 3 is a normal operation. Option 2 is also fine as no write operation is involved. Option 1 can be recovered, but option 4 can’t be.

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