第19集MongoDB副本集迁移实操案例

// MongoDB副本集迁移策略分析
class MongoDBMigrationStrategy {
    constructor() {
        this.strategies = {
            // 滚动迁移
            rollingMigration: {
                description: '逐个节点迁移，保持服务可用',
                advantages: ['零停机时间', '风险较低', '可回滚'],
                disadvantages: ['迁移时间长', '资源消耗大'],
                applicable: '生产环境，对可用性要求高'
            },
            
            // 全量迁移
            fullMigration: {
                description: '整体迁移到新环境',
                advantages: ['迁移时间短', '资源消耗少'],
                disadvantages: ['需要停机时间', '风险较高'],
                applicable: '测试环境，可接受短暂停机'
            },
            
            // 增量迁移
            incrementalMigration: {
                description: '先全量后增量同步',
                advantages: ['数据一致性保证', '可控制迁移进度'],
                disadvantages: ['操作复杂', '需要额外存储'],
                applicable: '大数据量迁移，对一致性要求高'
            }
        };
    }
    
    // 选择迁移策略
    selectStrategy(scenario) {
        const { environment, downtimeAcceptable, dataSize, consistencyRequirement } = scenario;
        
        if (environment === 'production' && !downtimeAcceptable) {
            return 'rollingMigration';
        } else if (dataSize > 1000 && consistencyRequirement === 'high') {
            return 'incrementalMigration';
        } else {
            return 'fullMigration';
        }
    }
    
    // 评估迁移风险
    assessRisk(strategy, scenario) {
        const risks = {
            rollingMigration: ['网络中断', '节点故障', '数据不一致'],
            fullMigration: ['数据丢失', '服务中断', '回滚困难'],
            incrementalMigration: ['同步延迟', '存储不足', '操作复杂']
        };
        
        return {
            strategy,
            risks: risks[strategy],
            mitigation: this.getMitigationMeasures(strategy)
        };
    }
    
    // 获取风险缓解措施
    getMitigationMeasures(strategy) {
        const measures = {
            rollingMigration: [
                '提前备份数据',
                '监控网络状态',
                '准备回滚方案',
                '分阶段验证'
            ],
            fullMigration: [
                '完整数据备份',
                '制定回滚计划',
                '测试迁移流程',
                '准备应急方案'
            ],
            incrementalMigration: [
                '监控同步状态',
                '预留足够存储',
                '详细操作文档',
                '分步验证数据'
            ]
        };
        
        return measures[strategy];
    }
}

// 使用迁移策略
const migrationStrategy = new MongoDBMigrationStrategy();

const scenario = {
    environment: 'production',
    downtimeAcceptable: false,
    dataSize: 500, // GB
    consistencyRequirement: 'high'
};

const selectedStrategy = migrationStrategy.selectStrategy(scenario);
const riskAssessment = migrationStrategy.assessRisk(selectedStrategy, scenario);

console.log('选择的迁移策略:', selectedStrategy);
console.log('风险评估:', riskAssessment);

// MongoDB滚动迁移流程
class RollingMigrationProcess {
    constructor() {
        this.steps = [
            '环境准备',
            '新节点部署',
            '数据同步',
            '节点切换',
            '旧节点下线',
            '验证测试'
        ];
        
        this.currentStep = 0;
        this.migrationLog = [];
    }
    
    // 执行迁移步骤
    async executeStep(stepName) {
        console.log(`执行步骤: ${stepName}`);
        
        try {
            switch (stepName) {
                case '环境准备':
                    await this.prepareEnvironment();
                    break;
                case '新节点部署':
                    await this.deployNewNodes();
                    break;
                case '数据同步':
                    await this.syncData();
                    break;
                case '节点切换':
                    await this.switchNodes();
                    break;
                case '旧节点下线':
                    await this.removeOldNodes();
                    break;
                case '验证测试':
                    await this.validateMigration();
                    break;
            }
            
            this.migrationLog.push({
                step: stepName,
                status: 'success',
                timestamp: new Date()
            });
            
        } catch (error) {
            this.migrationLog.push({
                step: stepName,
                status: 'failed',
                error: error.message,
                timestamp: new Date()
            });
            throw error;
        }
    }
    
    // 环境准备
    async prepareEnvironment() {
        console.log('1. 检查目标环境');
        console.log('2. 安装MongoDB');
        console.log('3. 配置网络');
        console.log('4. 准备存储');
        
        // 模拟环境准备
        await this.delay(2000);
    }
    
    // 部署新节点
    async deployNewNodes() {
        console.log('1. 部署新MongoDB节点');
        console.log('2. 配置副本集');
        console.log('3. 启动服务');
        console.log('4. 验证节点状态');
        
        // 模拟节点部署
        await this.delay(3000);
    }
    
    // 数据同步
    async syncData() {
        console.log('1. 初始化同步');
        console.log('2. 监控同步进度');
        console.log('3. 验证数据一致性');
        console.log('4. 完成同步');
        
        // 模拟数据同步
        await this.delay(5000);
    }
    
    // 节点切换
    async switchNodes() {
        console.log('1. 添加新节点到副本集');
        console.log('2. 等待新节点同步');
        console.log('3. 切换主节点');
        console.log('4. 验证切换结果');
        
        // 模拟节点切换
        await this.delay(2000);
    }
    
    // 移除旧节点
    async removeOldNodes() {
        console.log('1. 从副本集移除旧节点');
        console.log('2. 停止旧节点服务');
        console.log('3. 清理旧节点数据');
        console.log('4. 释放资源');
        
        // 模拟节点移除
        await this.delay(1500);
    }
    
    // 验证迁移
    async validateMigration() {
        console.log('1. 检查副本集状态');
        console.log('2. 验证数据完整性');
        console.log('3. 测试读写操作');
        console.log('4. 性能基准测试');
        
        // 模拟验证过程
        await this.delay(1000);
    }
    
    // 延迟函数
    delay(ms) {
        return new Promise(resolve => setTimeout(resolve, ms));
    }
    
    // 获取迁移日志
    getMigrationLog() {
        return this.migrationLog;
    }
}

// 使用滚动迁移
const migration = new RollingMigrationProcess();

// 执行迁移
async function executeMigration() {
    for (const step of migration.steps) {
        try {
            await migration.executeStep(step);
            console.log(`步骤 ${step} 完成`);
        } catch (error) {
            console.error(`步骤 ${step} 失败:`, error.message);
            break;
        }
    }
    
    console.log('迁移日志:', migration.getMigrationLog());
}

// executeMigration();

// MongoDB增量迁移实现
class IncrementalMigration {
    constructor() {
        this.sourceConnection = null;
        this.targetConnection = null;
        this.syncStatus = {
            isRunning: false,
            lastSyncTime: null,
            syncCount: 0,
            errorCount: 0
        };
    }
    
    // 初始化连接
    async initializeConnections() {
        console.log('初始化数据库连接...');
        
        // 连接源数据库
        this.sourceConnection = await this.connectToDatabase('source');
        
        // 连接目标数据库
        this.targetConnection = await this.connectToDatabase('target');
        
        console.log('数据库连接初始化完成');
    }
    
    // 连接数据库
    async connectToDatabase(type) {
        const config = type === 'source' ? 
            { host: 'source1:27017', replicaSet: 'source-rs' } :
            { host: 'target1:27017', replicaSet: 'target-rs' };
        
        // 模拟数据库连接
        return {
            type,
            config,
            connected: true
        };
    }
    
    // 全量同步
    async fullSync() {
        console.log('开始全量同步...');
        
        try {
            // 获取所有数据库
            const databases = await this.getDatabases();
            
            for (const db of databases) {
                console.log(`同步数据库: ${db.name}`);
                
                // 获取数据库中的所有集合
                const collections = await this.getCollections(db.name);
                
                for (const collection of collections) {
                    console.log(`同步集合: ${collection.name}`);
                    
                    // 同步集合数据
                    await this.syncCollection(db.name, collection.name);
                }
            }
            
            console.log('全量同步完成');
            
        } catch (error) {
            console.error('全量同步失败:', error);
            throw error;
        }
    }
    
    // 增量同步
    async incrementalSync() {
        console.log('开始增量同步...');
        
        this.syncStatus.isRunning = true;
        
        try {
            while (this.syncStatus.isRunning) {
                // 获取oplog
                const oplogEntries = await this.getOplogEntries();
                
                for (const entry of oplogEntries) {
                    await this.processOplogEntry(entry);
                }
                
                // 更新同步状态
                this.syncStatus.lastSyncTime = new Date();
                this.syncStatus.syncCount += oplogEntries.length;
                
                // 等待下次同步
                await this.delay(1000);
            }
            
        } catch (error) {
            this.syncStatus.errorCount++;
            console.error('增量同步错误:', error);
        }
    }
    
    // 获取oplog条目
    async getOplogEntries() {
        // 模拟获取oplog条目
        return [
            {
                ts: new Date(),
                op: 'i', // insert
                ns: 'test.users',
                o: { _id: 1, name: 'John', age: 30 }
            },
            {
                ts: new Date(),
                op: 'u', // update
                ns: 'test.users',
                o2: { _id: 1 },
                o: { $set: { age: 31 } }
            }
        ];
    }
    
    // 处理oplog条目
    async processOplogEntry(entry) {
        try {
            switch (entry.op) {
                case 'i': // insert
                    await this.insertDocument(entry.ns, entry.o);
                    break;
                case 'u': // update
                    await this.updateDocument(entry.ns, entry.o2, entry.o);
                    break;
                case 'd': // delete
                    await this.deleteDocument(entry.ns, entry.o);
                    break;
            }
        } catch (error) {
            console.error('处理oplog条目失败:', error);
            throw error;
        }
    }
    
    // 插入文档
    async insertDocument(namespace, document) {
        console.log(`插入文档到 ${namespace}:`, document);
        // 实际实现中会调用MongoDB的insert操作
    }
    
    // 更新文档
    async updateDocument(namespace, query, update) {
        console.log(`更新文档 ${namespace}:`, query, update);
        // 实际实现中会调用MongoDB的update操作
    }
    
    // 删除文档
    async deleteDocument(namespace, query) {
        console.log(`删除文档 ${namespace}:`, query);
        // 实际实现中会调用MongoDB的delete操作
    }
    
    // 同步集合
    async syncCollection(database, collection) {
        console.log(`同步集合 ${database}.${collection}`);
        
        // 获取集合中的所有文档
        const documents = await this.getCollectionDocuments(database, collection);
        
        // 批量插入到目标数据库
        await this.batchInsert(database, collection, documents);
    }
    
    // 获取数据库列表
    async getDatabases() {
        // 模拟获取数据库列表
        return [
            { name: 'test', sizeOnDisk: 1024000 },
            { name: 'admin', sizeOnDisk: 512000 }
        ];
    }
    
    // 获取集合列表
    async getCollections(database) {
        // 模拟获取集合列表
        return [
            { name: 'users' },
            { name: 'orders' }
        ];
    }
    
    // 获取集合文档
    async getCollectionDocuments(database, collection) {
        // 模拟获取文档
        return [
            { _id: 1, name: 'John', age: 30 },
            { _id: 2, name: 'Jane', age: 25 }
        ];
    }
    
    // 批量插入
    async batchInsert(database, collection, documents) {
        console.log(`批量插入 ${documents.length} 个文档到 ${database}.${collection}`);
        // 实际实现中会调用MongoDB的批量插入操作
    }
    
    // 停止同步
    stopSync() {
        this.syncStatus.isRunning = false;
        console.log('增量同步已停止');
    }
    
    // 获取同步状态
    getSyncStatus() {
        return this.syncStatus;
    }
    
    // 延迟函数
    delay(ms) {
        return new Promise(resolve => setTimeout(resolve, ms));
    }
}

// 使用增量迁移
const incrementalMigration = new IncrementalMigration();

// 执行增量迁移
async function executeIncrementalMigration() {
    try {
        // 初始化连接
        await incrementalMigration.initializeConnections();
        
        // 全量同步
        await incrementalMigration.fullSync();
        
        // 增量同步
        await incrementalMigration.incrementalSync();
        
    } catch (error) {
        console.error('增量迁移失败:', error);
    }
}

// executeIncrementalMigration();

// MongoDB迁移监控系统
class MigrationMonitor {
    constructor() {
        this.metrics = {
            migrationProgress: 0,
            dataTransferred: 0,
            errorCount: 0,
            startTime: null,
            endTime: null
        };
        
        this.alerts = [];
        this.thresholds = {
            maxErrorRate: 0.05, // 5%
            maxDowntime: 300,   // 5分钟
            minThroughput: 100   // MB/s
        };
    }
    
    // 开始监控
    startMonitoring() {
        console.log('开始监控MongoDB迁移...');
        
        this.metrics.startTime = new Date();
        
        // 启动各种监控
        this.monitorReplicaSetStatus();
        this.monitorDataTransfer();
        this.monitorErrorRate();
        this.monitorPerformance();
    }
    
    // 监控副本集状态
    monitorReplicaSetStatus() {
        setInterval(() => {
            this.checkReplicaSetHealth();
        }, 30000); // 每30秒检查一次
    }
    
    // 检查副本集健康状态
    async checkReplicaSetHealth() {
        try {
            // 检查源副本集
            const sourceStatus = await this.getReplicaSetStatus('source');
            this.analyzeReplicaSetStatus('source', sourceStatus);
            
            // 检查目标副本集
            const targetStatus = await this.getReplicaSetStatus('target');
            this.analyzeReplicaSetStatus('target', targetStatus);
            
        } catch (error) {
            this.handleAlert('replica_set_error', error.message);
        }
    }
    
    // 获取副本集状态
    async getReplicaSetStatus(type) {
        const config = type === 'source' ? 
            { host: 'source1:27017', replicaSet: 'source-rs' } :
            { host: 'target1:27017', replicaSet: 'target-rs' };
        
        // 模拟获取副本集状态
        return {
            members: [
                { name: 'node1:27017', stateStr: 'PRIMARY', health: 1 },
                { name: 'node2:27017', stateStr: 'SECONDARY', health: 1 },
                { name: 'node3:27017', stateStr: 'SECONDARY', health: 1 }
            ],
            ok: 1
        };
    }
    
    // 分析副本集状态
    analyzeReplicaSetStatus(type, status) {
        const unhealthyMembers = status.members.filter(member => member.health !== 1);
        
        if (unhealthyMembers.length > 0) {
            this.handleAlert('unhealthy_member', 
                `${type}副本集有${unhealthyMembers.length}个不健康的节点`);
        }
        
        const primaryCount = status.members.filter(member => 
            member.stateStr === 'PRIMARY').length;
        
        if (primaryCount !== 1) {
            this.handleAlert('primary_count_error', 
                `${type}副本集主节点数量异常: ${primaryCount}`);
        }
    }
    
    // 监控数据传输
    monitorDataTransfer() {
        setInterval(() => {
            this.calculateDataTransferRate();
        }, 10000); // 每10秒计算一次
    }
    
    // 计算数据传输速率
    calculateDataTransferRate() {
        const currentTime = new Date();
        const timeDiff = (currentTime - this.metrics.startTime) / 1000; // 秒
        
        if (timeDiff > 0) {
            const transferRate = this.metrics.dataTransferred / timeDiff; // MB/s
            
            if (transferRate < this.thresholds.minThroughput) {
                this.handleAlert('low_throughput', 
                    `数据传输速率过低: ${transferRate.toFixed(2)} MB/s`);
            }
        }
    }
    
    // 监控错误率
    monitorErrorRate() {
        setInterval(() => {
            this.calculateErrorRate();
        }, 60000); // 每分钟计算一次
    }
    
    // 计算错误率
    calculateErrorRate() {
        const totalOperations = this.metrics.dataTransferred + this.metrics.errorCount;
        
        if (totalOperations > 0) {
            const errorRate = this.metrics.errorCount / totalOperations;
            
            if (errorRate > this.thresholds.maxErrorRate) {
                this.handleAlert('high_error_rate', 
                    `错误率过高: ${(errorRate * 100).toFixed(2)}%`);
            }
        }
    }
    
    // 监控性能
    monitorPerformance() {
        setInterval(() => {
            this.checkPerformanceMetrics();
        }, 15000); // 每15秒检查一次
    }
    
    // 检查性能指标
    async checkPerformanceMetrics() {
        try {
            // 检查连接数
            const connectionCount = await this.getConnectionCount();
            if (connectionCount > 1000) {
                this.handleAlert('high_connections', 
                    `连接数过高: ${connectionCount}`);
            }
            
            // 检查内存使用
            const memoryUsage = await this.getMemoryUsage();
            if (memoryUsage > 0.9) {
                this.handleAlert('high_memory_usage', 
                    `内存使用率过高: ${(memoryUsage * 100).toFixed(2)}%`);
            }
            
            // 检查磁盘使用
            const diskUsage = await this.getDiskUsage();
            if (diskUsage > 0.8) {
                this.handleAlert('high_disk_usage', 
                    `磁盘使用率过高: ${(diskUsage * 100).toFixed(2)}%`);
            }
            
        } catch (error) {
            this.handleAlert('performance_check_error', error.message);
        }
    }
    
    // 获取连接数
    async getConnectionCount() {
        // 模拟获取连接数
        return Math.floor(Math.random() * 1500) + 500;
    }
    
    // 获取内存使用率
    async getMemoryUsage() {
        // 模拟获取内存使用率
        return Math.random() * 0.5 + 0.3;
    }
    
    // 获取磁盘使用率
    async getDiskUsage() {
        // 模拟获取磁盘使用率
        return Math.random() * 0.3 + 0.4;
    }
    
    // 处理告警
    handleAlert(type, message) {
        const alert = {
            type,
            message,
            timestamp: new Date(),
            severity: this.getAlertSeverity(type)
        };
        
        this.alerts.push(alert);
        
        console.log(`[${alert.severity}] ${type}: ${message}`);
        
        // 发送告警通知
        this.sendAlertNotification(alert);
    }
    
    // 获取告警严重程度
    getAlertSeverity(type) {
        const severityMap = {
            'replica_set_error': 'CRITICAL',
            'unhealthy_member': 'HIGH',
            'primary_count_error': 'CRITICAL',
            'low_throughput': 'MEDIUM',
            'high_error_rate': 'HIGH',
            'high_connections': 'MEDIUM',
            'high_memory_usage': 'HIGH',
            'high_disk_usage': 'HIGH',
            'performance_check_error': 'MEDIUM'
        };
        
        return severityMap[type] || 'LOW';
    }
    
    // 发送告警通知
    sendAlertNotification(alert) {
        // 模拟发送告警通知
        console.log(`发送告警通知: ${alert.type} - ${alert.message}`);
        
        // 实际实现中会发送邮件、短信或推送到监控系统
    }
    
    // 获取监控报告
    getMonitoringReport() {
        const duration = this.metrics.endTime ? 
            (this.metrics.endTime - this.metrics.startTime) / 1000 : 
            (new Date() - this.metrics.startTime) / 1000;
        
        return {
            duration: `${duration.toFixed(2)} 秒`,
            progress: `${this.metrics.migrationProgress.toFixed(2)}%`,
            dataTransferred: `${this.metrics.dataTransferred.toFixed(2)} MB`,
            errorCount: this.metrics.errorCount,
            errorRate: this.metrics.errorCount / (this.metrics.dataTransferred + this.metrics.errorCount),
            alerts: this.alerts,
            status: this.getOverallStatus()
        };
    }
    
    // 获取整体状态
    getOverallStatus() {
        const criticalAlerts = this.alerts.filter(alert => alert.severity === 'CRITICAL');
        const highAlerts = this.alerts.filter(alert => alert.severity === 'HIGH');
        
        if (criticalAlerts.length > 0) {
            return 'CRITICAL';
        } else if (highAlerts.length > 2) {
            return 'WARNING';
        } else {
            return 'HEALTHY';
        }
    }
    
    // 停止监控
    stopMonitoring() {
        this.metrics.endTime = new Date();
        console.log('MongoDB迁移监控已停止');
    }
}

// 使用监控系统
const monitor = new MigrationMonitor();

// 开始监控
monitor.startMonitoring();

// 模拟迁移过程
setTimeout(() => {
    monitor.metrics.migrationProgress = 50;
    monitor.metrics.dataTransferred = 1000;
    monitor.metrics.errorCount = 5;
}, 30000);

// 获取监控报告
setTimeout(() => {
    const report = monitor.getMonitoringReport();
    console.log('监控报告:', report);
    monitor.stopMonitoring();
}, 60000);