Atomicity
All-or-nothing, no partial results.
- E.g. in a money transfer, debit one account, credit the other. Either debit and credit both run, or neither runs.
- Successful completion is called Commit.
- Transaction failure is called Abort.
Commit and abort are irrevocable actions.
An Abort undoes operations that already executed
- For database operations, restore the data’s previous value from before the transaction
- But some real world operations are not undoable.Examples - transfer money, print ticket, fire missile