How to use MySQL's distributed transaction to handle cross-database transactions

How to use MySQL's distributed transaction to process cross-database transactions

Introduction:
With the rapid development of the Internet, a large number of application systems need to support the processing of massive data and high concurrent access. In this case, traditional single-database transactions can no longer meet the requirements of the system, and distributed transactions have become an essential choice. As one of the most commonly used relational databases, MySQL provides a distributed transaction solution. This article will introduce how to use MySQL's distributed transaction to process cross-database transactions and give corresponding code examples.

1. Overview of distributed transactions
Distributed transactions refer to a transaction that spans multiple databases, and each database must maintain a consistent state during transaction execution. This requires the use of distributed transactions in distributed systems to ensure data consistency and reliability. In MySQL, distributed transactions can be implemented using the XA protocol.

2. XA Protocol
XA (eXtended Architecture) is a distributed transaction specification used to achieve transaction consistency in a distributed environment. MySQL provides support for XA transactions, allowing us to perform distributed transaction operations between multiple MySQL instances.

3. Basic process of distributed transactions

1. Start a distributed transaction: call the XA START statement to start a new distributed transaction.
2. Perform transaction operations: Perform database operations within a transaction, including reading and modifying data.
3. Commit or rollback the transaction: Based on the execution of the transaction, call the XA END and XA PREPARE statements to commit or rollback the transaction.
4. Finally commit or rollback the transaction: After all participants have called XA PREPARE, XA COMMIT or XA ROLLBACK can be called to finally commit or rollback the transaction.

4. Sample code
The following is a sample code that uses MySQL's distributed transaction to process cross-database transactions:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class XATransactionExample {

    public static void main(String[] args) {
        Connection conn1 = null;
        Connection conn2 = null;

        try {
            // 加载MySQL驱动
            Class.forName("com.mysql.cj.jdbc.Driver");

            // 获取连接1
            conn1 = DriverManager.getConnection("jdbc:mysql://localhost:3306/db1", "user1", "password1");

            // 获取连接2
            conn2 = DriverManager.getConnection("jdbc:mysql://localhost:3306/db2", "user2", "password2");

            // 开启分布式事务
            conn1.setAutoCommit(false);
            conn2.setAutoCommit(false);

            // 在连接1上执行事务操作
            // ...

            // 在连接2上执行事务操作
            // ...

            // 提交事务
            conn1.commit();
            conn2.commit();

        } catch (Exception e) {
            try {
                System.err.println("事务失败，回滚事务");
                // 回滚事务
                if (conn1 != null) {
                    conn1.rollback();
                }
                if (conn2 != null) {
                    conn2.rollback();
                }
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
            e.printStackTrace();
        } finally {
            try {
                // 关闭连接
                if (conn1 != null) {
                    conn1.close();
                }
                if (conn2 != null) {
                    conn2.close();
                }
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
        }
    }
}

5. Summary
Through the introduction of this article and sample code, we learned how to use MySQL's distributed transactions to handle cross-database transactions. Distributed transactions can ensure data consistency and reliability in the database, which is very important for large application systems. In actual development, we can choose appropriate distributed transaction solutions based on specific needs and situations to improve system performance and scalability.

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