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C20.0046: Database Management Systems Lecture #1 - page 17 / 40

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M.P. Johnson, DBMS, Stern/NYU, Sp2004

17

Atomicity & Durability

Saw how George lost $100 with makeshift DBMS

DBMS prevents this outcome

xacts are all or nothing

One idea: Keep a log (history) of all actions in set of xacts

Durability: Use log to redo or undo certain ops in crash recovery

Atomicity: don’t really commit changes until end

Then, all at once

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