MySQL主从同步与分库分表原理及实现方法

-- 在主库插入测试数据
INSERT INTO test_table (id, name) VALUES (1, 'test');
-- 在从库查询数据
SELECT * FROM test_table WHERE id=1;

-- 创建用户库和订单库
CREATE DATABASE user_db;
CREATE DATABASE order_db;
-- 将用户表迁移到用户库
RENAME TABLE original_db.user TO user_db.user;
-- 将订单表迁移到订单库
RENAME TABLE original_db.order TO order_db.order;

// 用户操作使用user_db连接
DataSource userDataSource = setupDataSource("user_db");
// 订单操作使用order_db连接
DataSource orderDataSource = setupDataSource("order_db");

CREATE TABLE user (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50),
    email VARCHAR(100),
    phone VARCHAR(20),
    address TEXT,
    profile JSON,
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

-- 核心信息表
CREATE TABLE user Core (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    name VARCHAR(50),
    email VARCHAR(100),
    phone VARCHAR(20),
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
);
-- 扩展信息表
CREATE TABLE user Extend (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    user_id BIGINT,
    address TEXT,
    profile JSON,
    FOREIGN KEY (user_id) REFERENCES user Core(id)
);

-- 创建4张分表
CREATE TABLE user_001 (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    user_id BIGINT,
    name VARCHAR(50),
    email VARCHAR(100),
    phone VARCHAR(20),
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB;
-- 类似创建user_002、user_003、user_004表
-- 设置主键步长避免冲突
ALTER TABLE user_001 AUTO_INCREMENT=1;
ALTER TABLE user_002 AUTO_INCREMENT=2;
ALTER TABLE user_003 AUTO_INCREMENT=3;
ALTER TABLE user_004 AUTO_INCREMENT=4;
-- 设置全局步长
SET GLOBAL auto_increment_increment=4;

public class UserDAO {
    private static final int SHARD_COUNT = 4;
    // 获取分片编号
    private int getShardNumber(long userId) {
        return (int) (userId % SHARD_COUNT);
    }
    // 插入用户
    public void insertUser(User user) {
        int shardNumber = getShardNumber(user.getId());
        String table = "user_" + String.format("%03d", shardNumber);
        try (Connection conn = getDataSource(shardNumber). connections()) {
            conn预备语句(
                "INSERT INTO " + table + " (user_id, name, email, phone) " +
                "VALUES (?, ?, ?, ?)"
            ). executeUpdate();
        }
    }
    // 查询用户
    public User getUser(long userId) {
        int shardNumber = getShardNumber(userId);
        String table = "user_" + String.format("%03d", shardNumber);
        try (Connection conn = getDataSource(shardNumber). connections()) {
           预备语句ps = conn预备语句(
                "SELECT * FROM " + table + " WHERE user_id = ?"
            );
            ps.setLong(1, userId);
            结果集rs = ps执行查询();
            if (rs.next()) {
                return mapToUser(rs);
            }
        }
        return null;
    }
    // 获取对应分片的数据库连接
    private DataSource getDataSource(int shardNumber) {
        switch (shardNumber) {
            case 0:
                return userDataSource0;
            case 1:
                return userDataSource1;
            case 2:
                return userDataSource2;
            case 3:
                return userDataSource3;
            default:
                throw new IllegalArgumentException("无效的分片编号");
        }
    }
}

SET GLOBAL auto_increment_increment = 4;

ALTER TABLE user_001 AUTO_INCREMENT = 1;
ALTER TABLE user_002 AUTO_INCREMENT = 5;
ALTER TABLE user_003 AUTO_INCREMENT = 9;
ALTER TABLE user_004 AUTO_INCREMENT = 13;

# 主库IP: 192.168.1.100
# 从库IP: 192.168.1.101
# 安装MySQL 8.0
sudo yum install mysql-server
sudo systemctl start mysqld
sudo systemctl enable mysqld

# 获取初始化密码
sudo grep 'temporary password' /var/log/mysqld.log
# 登录MySQL
mysql -u root -p
# 修改root密码
ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'NewPassword123';
# 创建复制用户
CREATE USER 'repl'@'192.168.1.%' IDENTIFIED WITH mysql_native_password BY 'ReplPassword123';
GRANT REPLICATION SLAVE ON *.* TO 'repl'@'192.168.1.%';
FLUSH PRIVILEGES;
# 修改my.cnf配置文件
sudo vi /etc/my.cnf
# 添加以下配置
[mysqld]
server-id=1
log-bin=mysql-bin
binlog-do-db=your_db
binlog-checksum=NONE
binlog-format=ROW
sync_binlog=1
innodb_flush_log_at_trx_commit=1
gtid_mode=ON
enforce_gtid_consistency=ON

# 修改my.cnf配置文件
sudo vi /etc/my.cnf
# 添加以下配置
[mysqld]
server-id=2
log-bin=mysql-bin
replicate-do-db=your_db
replicate_binlog checksum=0
replicate_binlog format=MIXED
gtid_mode=ON
enforce_gtid_consistency=ON
read-only=ON

# 主库导出数据
mysqldump -u root -p --single-transaction your_db > dump.sql
# 从库导入数据
mysql -u root -p your_db < dump.sql
# 从库设置主库信息
CHANGE MASTER TO
    MASTER_HOST='192.168.1.100',
    MASTER_USER='repl',
    MASTER_PASSWORD='ReplPassword123',
    MASTER AUTO_POSITION=1;
# 启动从库复制
START SLAVE;
# 检查复制状态
SHOW SLAVE STATUS\G

-- 创建分片表
CREATE TABLE user_001 (
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    user_id BIGINT,
    name VARCHAR(50),
    email VARCHAR(100),
    phone VARCHAR(20),
    created_at DATETIME DEFAULT CURRENT_TIMESTAMP
) ENGINE=InnoDB;
-- 创建其他分片表
CREATE TABLE user_002 LIKE user_001;
CREATE TABLE user_003 LIKE user_001;
CREATE TABLE user_004 LIKE user_001;
-- 设置主键步长
ALTER TABLE user_001 AUTO_INCREMENT=1;
ALTER TABLE user_002 AUTO_INCREMENT=5;
ALTER TABLE user_003 AUTO_INCREMENT=9;
ALTER TABLE user_004 AUTO_INCREMENT=13;
-- 设置全局步长
SET GLOBAL auto_increment_increment=4;

// 使用ShardingSphere的ShardingSphereDataSource
ShardingSphereDataSource dataSource = ShardingSphereDataSourceFactory.createDataSource(
    createDataSourceMap(),
    createRuleConfiguration(),
    new Properties()
);
// 插入用户
public void insertUser(User user) {
    try (Connection conn = dataSource.getConnection()) {
        conn预备语句(
            "INSERT INTO t_user (user_id, name, email, phone) " +
            "VALUES (?, ?, ?, ?)"
        ). executeUpdate();
    }
}
// 查询用户
public User getUser(long userId) {
    try (Connection conn = dataSource.getConnection()) {
       预备语句ps = conn预备语句(
            "SELECT * FROM t_user WHERE user_id = ?"
        );
        ps.setLong(1, userId);
        结果集rs = ps执行查询();
        if (rs.next()) {
            return mapToUser(rs);
        }
    }
    return null;
}

# ShardingSphere配置文件
rules:
- !SHARDING
  tables:
    t_user:
      actualDataNodes: ds_${0..3}.t_user_${0..3}
      tableStrategy:
        standard:
          shardingColumn: user_id
          shardingAlgorithmName: inline
  shardingAlgorithms:
    inline:
      type: INLINE
      props:
        algorithm-expression: t_user_${user_id % 4}