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Transactions and Buffer Pool (cont)

Handling stealing:
  • transaction T loads page P and makes changes
  • T2 needs a buffer, and P is the "victim"
  • P is output to disk (it's dirty) and replaced
  • if T aborts, some of its changes are already "committed"
  • must log values changed by T in P at "steal-time"
  • use these to UNDO changes in case of failure of T