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MySQL数据库容灾设计案例与SQL实现

一、主从复制容灾方案

1. 配置主从复制

-- 在主库执行（创建复制账号）
CREATE USER 'repl_user'@'%' IDENTIFIED BY 'SecurePass123!';
GRANT REPLICATION SLAVE ON *.* TO 'repl_user'@'%';-- 查看主库状态（记录File和Position）
SHOW MASTER STATUS;
-- 示例输出：
-- File: mysql-bin.000001
-- Position: 107-- 在从库执行配置
CHANGE MASTER TO
MASTER_HOST='master_host',
MASTER_USER='repl_user',
MASTER_PASSWORD='SecurePass123!',
MASTER_LOG_FILE='mysql-bin.000001',
MASTER_LOG_POS=107;-- 启动从库复制
START SLAVE;-- 检查从库状态
SHOW SLAVE STATUS\G

2. 自动故障转移检测

-- 创建监控表
CREATE TABLE replication_monitor (id INT AUTO_INCREMENT PRIMARY KEY,check_time DATETIME DEFAULT CURRENT_TIMESTAMP,master_status VARCHAR(20),slave_io_running VARCHAR(3),slave_sql_running VARCHAR(3),seconds_behind INT,last_error TEXT
);-- 创建监控存储过程
DELIMITER //
CREATE PROCEDURE check_replication_status()
BEGINDECLARE io_status VARCHAR(3);DECLARE sql_status VARCHAR(3);DECLARE behind INT;-- 获取从库状态SELECT Slave_IO_Running, Slave_SQL_Running, Seconds_Behind_MasterINTO io_status, sql_status, behindFROM performance_schema.replication_applier_status;-- 记录状态INSERT INTO replication_monitor (master_status, slave_io_running, slave_sql_running, seconds_behind)VALUES ('OK', io_status, sql_status, behind);-- 如果复制中断，发送警报IF io_status != 'Yes' OR sql_status != 'Yes' THENINSERT INTO alert_logs (alert_type, alert_message)VALUES ('REPLICATION_ERROR', CONCAT('Replication error - IO: ', io_status, ', SQL: ', sql_status));END IF;
END //
DELIMITER ;-- 创建定时事件
CREATE EVENT ev_replication_monitor
ON SCHEDULE EVERY 1 MINUTE
DO CALL check_replication_status();

二、MGR(MySQL Group Replication)高可用方案

1. 初始化MGR集群

-- 在所有节点执行基础配置
SET SQL_LOG_BIN=0;
CREATE USER 'mgr_user'@'%' IDENTIFIED BY 'MgrSecurePass456!';
GRANT REPLICATION SLAVE ON *.* TO 'mgr_user'@'%';
GRANT BACKUP_ADMIN ON *.* TO 'mgr_user'@'%';
FLUSH PRIVILEGES;
SET SQL_LOG_BIN=1;-- 配置第一个节点（引导节点）
SET GLOBAL group_replication_bootstrap_group=ON;
START GROUP_REPLICATION USER='mgr_user', PASSWORD='MgrSecurePass456!';
SET GLOBAL group_replication_bootstrap_group=OFF;-- 其他节点加入集群
START GROUP_REPLICATION USER='mgr_user', PASSWORD='MgrSecurePass456!';-- 查看集群状态
SELECT * FROM performance_schema.replication_group_members;

2. MGR故障自动处理

-- 创建故障处理存储过程
DELIMITER //
CREATE PROCEDURE handle_mgr_failure()
BEGINDECLARE member_count INT;DECLARE primary_member VARCHAR(255);-- 检查集群成员数量SELECT COUNT(*) INTO member_count FROM performance_schema.replication_group_membersWHERE MEMBER_STATE = 'ONLINE';-- 如果少于2个在线成员，触发警报IF member_count < 2 THENINSERT INTO alert_logs (alert_type, alert_message)VALUES ('MGR_WARNING', CONCAT('Only ', member_count, ' members online'));-- 尝试自动恢复IF member_count = 0 THENSET GLOBAL group_replication_bootstrap_group=ON;START GROUP_REPLICATION;SET GLOBAL group_replication_bootstrap_group=OFF;END IF;END IF;-- 检查主节点是否存在SELECT MEMBER_HOST INTO primary_memberFROM performance_schema.replication_group_membersWHERE MEMBER_ROLE = 'PRIMARY' LIMIT 1;IF primary_member IS NULL THEN-- 触发选举新主节点STOP GROUP_REPLICATION;START GROUP_REPLICATION;END IF;
END //
DELIMITER ;-- 创建监控事件
CREATE EVENT ev_mgr_monitor
ON SCHEDULE EVERY 30 SECOND
DO CALL handle_mgr_failure();

三、跨机房容灾方案

1. 配置异地灾备

-- 主中心配置
CREATE USER 'dr_user'@'backup_center_IP' IDENTIFIED BY 'DrPass789!';
GRANT REPLICATION SLAVE ON *.* TO 'dr_user'@'backup_center_IP';-- 灾备中心配置（延迟复制，避免逻辑错误传播）
CHANGE MASTER TO
MASTER_HOST='primary_center_IP',
MASTER_USER='dr_user',
MASTER_PASSWORD='DrPass789!',
MASTER_DELAY=3600;  -- 延迟1小时START SLAVE;-- 配置半同步复制（确保数据安全）
-- 在主库执行
INSTALL PLUGIN rpl_semi_sync_master SONAME 'semisync_master.so';
SET GLOBAL rpl_semi_sync_master_enabled = 1;
SET GLOBAL rpl_semi_sync_master_timeout = 30000;  -- 30秒超时-- 在灾备库执行
INSTALL PLUGIN rpl_semi_sync_slave SONAME 'semisync_slave.so';
SET GLOBAL rpl_semi_sync_slave_enabled = 1;

2. 灾备切换流程

-- 1. 停止应用写入
-- 2. 确保所有数据同步完成
STOP SLAVE IO_THREAD;
SHOW PROCESSLIST;  -- 确保所有SQL线程完成-- 3. 提升灾备库为主库
STOP SLAVE;
RESET MASTER;  -- 清除复制信息
SET GLOBAL read_only = OFF;-- 4. 在原主库配置为新从库（故障恢复后）
CHANGE MASTER TO
MASTER_HOST='new_master_IP',
MASTER_USER='dr_user',
MASTER_PASSWORD='DrPass789!';START SLAVE;

四、数据校验与修复

1. 定期数据校验

-- 创建校验表
CREATE TABLE data_checksum (table_name VARCHAR(64) PRIMARY KEY,source_checksum BIGINT,target_checksum BIGINT,last_check_time DATETIME,status ENUM('OK', 'MISMATCH', 'NOT_CHECKED')
);-- 创建校验存储过程
DELIMITER //
CREATE PROCEDURE verify_data_consistency()
BEGINDECLARE done INT DEFAULT FALSE;DECLARE tname VARCHAR(64);DECLARE cur CURSOR FOR SELECT table_name FROM information_schema.tables WHERE table_schema = DATABASE() AND table_type = 'BASE TABLE';DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;OPEN cur;read_loop: LOOPFETCH cur INTO tname;IF done THENLEAVE read_loop;END IF;SET @sql = CONCAT('INSERT INTO data_checksum (table_name, source_checksum, last_check_time, status) VALUES (?, (SELECT COUNT(*) FROM ', tname, '), NOW(), ''NOT_CHECKED'') ON DUPLICATE KEY UPDATE source_checksum = VALUES(source_checksum), last_check_time = VALUES(last_check_time)');PREPARE stmt FROM @sql;EXECUTE stmt USING tname;DEALLOCATE PREPARE stmt;END LOOP;CLOSE cur;-- 标记不一致的表UPDATE data_checksum dcJOIN (SELECT table_name, COUNT(*) AS cnt FROM information_schema.tables WHERE table_schema = DATABASE() GROUP BY table_name) tON dc.table_name = t.table_nameSET dc.status = IF(dc.source_checksum = t.cnt, 'OK', 'MISMATCH');
END //
DELIMITER ;-- 创建定时校验任务
CREATE EVENT ev_data_verification
ON SCHEDULE EVERY 6 HOUR
DO CALL verify_data_consistency();

五、自动化容灾演练

-- 创建演练日志表
CREATE TABLE disaster_recovery_drill (drill_id INT AUTO_INCREMENT PRIMARY KEY,start_time DATETIME NOT NULL,end_time DATETIME,scenario VARCHAR(50) NOT NULL,status ENUM('RUNNING', 'SUCCESS', 'FAILED') DEFAULT 'RUNNING',details TEXT
);-- 创建演练存储过程
DELIMITER //
CREATE PROCEDURE execute_drill(IN scenario VARCHAR(50))
BEGINDECLARE drill_start DATETIME DEFAULT NOW();DECLARE drill_id INT;-- 记录演练开始INSERT INTO disaster_recovery_drill (start_time, scenario, status)VALUES (drill_start, scenario, 'RUNNING');SET drill_id = LAST_INSERT_ID();-- 根据场景执行不同操作CASE scenarioWHEN 'MASTER_FAILOVER' THEN-- 模拟主库故障SET @kill_id = (SELECT ID FROM information_schema.processlist WHERE USER = 'app_user' LIMIT 1);SET @sql = CONCAT('KILL ', @kill_id);PREPARE stmt FROM @sql;EXECUTE stmt;DEALLOCATE PREPARE stmt;-- 这里添加实际的故障转移逻辑-- ...UPDATE disaster_recovery_drill SET status = 'SUCCESS', end_time = NOW()WHERE drill_id = drill_id;WHEN 'DATACENTER_FAILURE' THEN-- 模拟数据中心故障-- ...ELSEUPDATE disaster_recovery_drill SET status = 'FAILED', end_time = NOW(),details = 'Unknown scenario'WHERE drill_id = drill_id;END CASE;
END //
DELIMITER ;

六、监控与告警系统

-- 创建监控仪表板视图
CREATE VIEW disaster_recovery_status AS
SELECT (SELECT COUNT(*) FROM replication_monitor WHERE slave_io_running = 'No' OR slave_sql_running = 'No') AS replication_errors,(SELECT COUNT(*) FROM performance_schema.replication_group_members WHERE MEMBER_STATE != 'ONLINE') AS mgr_offline_members,(SELECT COUNT(*) FROM data_checksum WHERE status = 'MISMATCH') AS data_mismatches,(SELECT MAX(TIMESTAMPDIFF(MINUTE, last_check_time, NOW())) FROM data_checksum) AS minutes_since_last_check,(SELECT COUNT(*) FROM alert_logs WHERE alert_time > DATE_SUB(NOW(), INTERVAL 1 HOUR)) AS recent_alerts;

以上SQL语句实现了一个完整的MySQL数据库容灾方案，包括主从复制、MGR高可用、异地灾备、数据校验和自动化演练等功能模块。实际应用时，需要根据具体环境调整IP地址、用户名密码等参数。