Page: 4 – Database Modification

  • Deferred Update

    • Actual DB update happens only after commit.

    • Easy recovery (just redo committed ones).

  • Immediate Update

    • Update DB before commit.

    • Needs both undo (for aborted txns) and redo (for committed txns).

Operations:

  • Undo → restore old value.

  • Redo → set new value again.

Updated on