Distributed Transactions

1. A coordinator node asks all participating services if they are prepared to commit, then — only if all agree — sends the final commit command. What protocol is this?

2. If the coordinator in a 2PC protocol crashes after sending prepare but before sending commit, participating nodes are blocked waiting. What is this problem called?

3. Instead of a single distributed transaction, the payment saga uses a sequence of local transactions: charge card → reserve inventory → confirm order. If inventory reservation fails, the saga refunds the card. What transaction design pattern is this?

4. A compensating transaction reverses the effect of a previously completed saga step when a later step fails. Which statement about compensating transactions is correct?

5. A transaction coordinator instructs all databases to lock resources and prepare to commit. One database confirms, but the third database crashes before responding. What must the coordinator do?