Go Tutorial Explains Two-Phase Commit by Simulating Cross-Database Bank Transfers

A hands-on guide published on DEV Community demonstrates the two-phase commit (2PC) protocol by building a small Go program that transfers funds between two accounts stored in separate databases — Alice in MySQL and Bob in PostgreSQL. The tutorial illustrates why a single database transaction cannot coordinate changes across different database systems, and how 2PC addresses this with a prepare phase and a decision phase managed by a central coordinator. In the prepare phase, each database saves its pending changes and signals readiness without finalising them, while the coordinator only issues a final commit or rollback once all participants have responded. The program also intentionally triggers crashes at critical moments to show how recovery mechanisms use a shared transaction name to resolve incomplete transfers consistently. The guide uses the XA standard for MySQL and PostgreSQL's PREPARE TRANSACTION commands to show how different databases implement the same underlying protocol.