Logging and Recovery: Motivation

• Atomicity:

  • Transactions may abort (“Rollback”).

• Durability:

  • What if DBMS stops running? (Causes?)

crash!

• Desired Behavior after system restarts:
  • T1, T2 & T3 should be durable.
  • T4 & T5 should be aborted (effects not seen).

T1

T2

T3

T4

T5

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