MongoDB 触发器，监听库/表变更记录

MongoDB 3.6版本之后支持Change Stream，，当MongoDB开启集群（副本集）时可以启用。此文记录Win10本地单进程MongoDB，监听指定表数据变更学习。

system: win10
MongoDB: v4.4.1
nodejs: v12.18.3.
python: v3.7.2

MongoDB副本集启动项

mongod.exe --dbpath ../data --replSet re0 --port 27020

MongoDB设置副本集

mongo.exe --port 27020
rs.initiate({ _id: "re0", members: [{_id:0,host:"127.0.0.1:27020"}]})
rs.status()

当控制台状态变为PRIMARY说明成功。

image.png

python版监听

# coding=utf-8
'''
Created on 2020年9月25日

@author: 瞌睡蟲子
'''
import pymongo

mongo_client = pymongo.MongoClient('127.0.0.1', 27020)
db = mongo_client['testDb']
col = db['testconn']
try:
    # with col.watch() as stream:
    with mongo_client.watch() as stream:
        for insert_change in stream:
            print(insert_change)
except pymongo.errors.PyMongoError as e:
    print(e)

nodejs版监听

const MongoClient = require("mongodb").MongoClient;
const url = "mongodb://127.0.0.1:27020";
const dbName = "testDb"
const tableName = "testconn"

const client = new MongoClient(url, { useNewUrlParser: true, useUnifiedTopology: true });

client.connect().then(db => {
    //const changeStream = client.db(dbName).collection(tableName).watch();
    const changeStream = client.watch();
    changeStream.on("change", next => {
        console.log(next);
    });
});

重点

1. 支持client，database，collection上都可以进行监听

with mongo_client.watch() as stream:

with db.watch() as stream:

with col.watch() as stream:

const changeStream = client.watch();

const changeStream = client.db(dbName).watch();

const changeStream = client.db(dbName).collection(tableName).watch();

2. watch内部过滤

watch([{ '$match': { 'operationType': { $in: ['insert', 'update'] }, "ns.db": "testDb", "ns.coll": "conn" } }]);

过滤结构匹配：testDb库，conn表，的insert或update操作。

参考：
https://www.mongodb.com/blog/post/five-minute-mongodb--change-streams-and-mongodb-4x
https://zhuanlan.zhihu.com/p/69610164