two phase commit (2PC)

Two-Phase-Commit (2PC) is a procedure for ensuring data consistency in distributed databases. This procedure is used for transactions to ensure that they are carried out consistently across multiple databases.

Two-Phase-Commit is a widespread protocol, which is used in manufacturer-specific versions. As can be seen from the name, distributed transactions take place in two phases. The first phase involves a partial transaction that is transmitted to the database systems. The data changesare made temporarily. During the partial transaction, the data is saved in such a way that no more data loss is possible. The partial transactions of the various database systems are confirmed by the coordination center.

In phase 2, the database systems complete the transactions and confirm this to the coordination center. The transaction is then completed when all confirmations have been received. Errors in the partial transactions are detected by the missing confirmation.