Mountebanking Cormorant
31/12/1969 • 21:00
The two-phase commit (2PC) protocol is a distributed transaction coordination protocol used in distributed databases and systems to ensure that a distributed transaction is either successfully committed at all participating nodes or completely aborted. The protocol involves two phases: the prepare phase and the commit phase. Here's how it works:
Prepare Phase:
The transaction coordinator, often referred to as the coordinator or coordinator node, sends a prepare request to all the participating nodes (also known as cohorts) involved in the transaction.
Each participating node then performs the necessary checks and validations to ensure that it can commit the transaction without any issues. This may include checking for sufficient resources, ensuring data consistency, and performing local validations.
After the participating nodes have completed their checks, they respond to the coordinator with either a "Yes" if they are prepared to commit or a "No" if they encounter any issues that prevent them from committing the transaction.
Commit Phase:
Based on the responses received during the prepare phase, the coordinator makes a decision to either commit or abort the transaction.
If all participating nodes responded with a "Yes" during the prepare phase, the coordinator sends a commit request to all nodes. This ensures that all nodes will commit the transaction.
If any node responded with a "No" during the prepare phase, the coordinator sends an abort request to all nodes, instructing them to roll back the transaction.
Prepare Phase:
The transaction coordinator, often referred to as the coordinator or coordinator node, sends a prepare request to all the participating nodes (also known as cohorts) involved in the transaction.
Each participating node then performs the necessary checks and validations to ensure that it can commit the transaction without any issues. This may include checking for sufficient resources, ensuring data consistency, and performing local validations.
After the participating nodes have completed their checks, they respond to the coordinator with either a "Yes" if they are prepared to commit or a "No" if they encounter any issues that prevent them from committing the transaction.
Commit Phase:
Based on the responses received during the prepare phase, the coordinator makes a decision to either commit or abort the transaction.
If all participating nodes responded with a "Yes" during the prepare phase, the coordinator sends a commit request to all nodes. This ensures that all nodes will commit the transaction.
If any node responded with a "No" during the prepare phase, the coordinator sends an abort request to all nodes, instructing them to roll back the transaction.