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Immediate database modification technique uses

  • A.Both undo and redo
  • B.Undo but no redo.
  • C.Redo but no undo.
  • D.Neither undo nor redo.

Answer: A

Correct answer: Both undo and redo

With immediate modification a transaction's writes reach the database before it commits, so an uncommitted transaction's changes must be undone after a crash, and a committed transaction's changes that had not yet reached disk must be redone. Deferred modification needs redo only, since nothing is written before commit.

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