如何使用MongoDB开发一个实时数据同步功能

// 导入MongoDB驱动
const MongoClient = require('mongodb').MongoClient;

// 定义副本集配置
const replicaSetConfig = {
  _id: 'rs0',
  members: [
    { _id: 0, host: 'mongo1:27017' },
    { _id: 1, host: 'mongo2:27017' },
    { _id: 2, host: 'mongo3:27017' }
  ]
};

// 创建MongoDB连接
const uri = 'mongodb://mongo1:27017,mongo2:27017,mongo3:27017/mydb?replicaSet=rs0';
const client = await MongoClient.connect(uri, { useUnifiedTopology: true });

// 初始化副本集
await client.db('admin').command({ replSetInitiate: replicaSetConfig });

// 创建数据源
const sourceDb = client.db('sourcedb');
const sourceCollection = sourceDb.collection('sourcecollection');

// 创建数据目标
const targetDb = client.db('targetdb');
const targetCollection = targetDb.collection('targetcollection');

// 创建变更流
const changeStream = sourceCollection.watch();

// 监听变更事件
changeStream.on('change', async (change) => {
  // 处理变更事件
  switch (change.operationType) {
    case 'insert':
      await targetCollection.insertOne(change.fullDocument);
      break;
    case 'update':
      await targetCollection.updateOne({ _id: change.documenTKEy._id }, { $set: change.fullDocument });
      break;
    case 'delete':
      await targetCollection.deleteOne({ _id: change.documentKey._id });
      break;
  }
});

// 启动数据同步
changeStream.resume();