All actions in txn happen, or none happen. Not to be confused with atomic in Multi Threading (which is more like isolation)


  • Use undo log
    • both in memory and on disk.
  • Shadow Paging
    • The DBMS makes copies of pages modified by the transactions and transactions make changes to those copies. Only when the transaction commits is the page made visible.
    • Slower runtime performance
    • Better recovery performance, single thread friendly.