# Transactions - Life Preservers

- ## Text Book:

  - system crash between one bank account being debited and another being credited.

- ## Dramatic:

  - power failure during update on 3 million rows when only part way through.

- ## Real-world:

  - complex series of inter-related updates, deletes and inserts on many separate tables fails at the last step due to a duplicate unique key on an insert.

- ## Locking alone won’t help you in any of these situations

  - (And locking with DBD::mysql < 2.1027 is unsafe due to auto reconnect)

- ## Transaction recovery would handle all these situations - automatically

  - Makes a system far more robust and trustworthy over the long term.

- ## Use transactions if your database supports them.

  - If it doesn't and you need them, switch to a different database.

## .

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