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Atomic Transactions

<aside> 💡 Up until both parties have signed on the dotted line (committed), either one can back out and it is as if nothing ever happened, but at the moment they both sign (commit), they pass the point of no return and the transaccion must be carried out.

This all-or-nothing property defines atomic transactions

</aside>

Properties of atomic transactions

• When a transaction is commited (everyone agrees to commit), the results are made permanent.
• If any process refuses (or crashes before agreement) the situation reverts to exactly the state it had before the transaction began (rollback to the initial state)

Transactions Primitives

Properties of Transactions

1. Atomic: Suceden o no suceden las transacciones completas
2. Consistent: Se cumplen las invariantes antes y despues de la transaccion (por ej la ley de conservacion del dinero)
3. Isolated (serializable): Ante el mundo externo, parecieran que las transacciones fueron ejecutadas secuencialmente. El scheduller se encarga de quedarse con escenarios validos
4. Durable: Los commits son permanentes.

Nested Transactions