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mongo变更流使用及windows下副本集五分钟搭建

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mongodb的变更流解释:

变更流（Change Streams）允许应用程序访问实时数据变更，从而避免事先手动追踪 oplog 的复杂性和风险。应用程序可使用变更流来订阅针对单个集合、数据库或整个部署的所有数据变更，并立即对它们做出响应。由于变更流采用聚合框架，因此，应用程序还可对特定变更进行过滤，或是随意转换通知。(Change Streams - MongoDB Manual v5.0)

使用场景,需要websocket推送实时数据的时候，我们把数据写入mongo的同时,websocket实时监听mongo数据，拿到后推送到订阅组用户。

这里只做一端新增另一端服务监听测试，及windows下副本集快速搭建流程。

sub端代码

package main

import (
	"context"
	"fmt"
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/mongo"
	"go.mongodb.org/mongo-driver/mongo/options"
	"log"
)

func main() {
	// 设置 MongoDB 客户端mongo单机模式不支持这种监听 单机报错 2024/08/10 11:18:54 (Location40573) The $changeStream stage is only supported on replica sets
	clientOptions := options.Client().ApplyURI("mongodb://localhost:27017")
	client, err := mongo.Connect(context.TODO(), clientOptions)
	if err != nil {
		log.Fatal(err)
	}
	defer client.Disconnect(context.TODO())

	// 获取数据库和集合
	collection := client.Database("testdb").Collection("items")

	// 设置 Change Stream
	pipeline := mongo.Pipeline{}
	changeStreamOptions := options.ChangeStream().SetFullDocument(options.UpdateLookup)
	changeStream, err := collection.Watch(context.TODO(), pipeline, changeStreamOptions)
	if err != nil {
		log.Fatal(err)
	}
	defer changeStream.Close(context.TODO())

	fmt.Println("开始监听 Change Stream...")

	// 读取 Change Stream
	for changeStream.Next(context.TODO()) {
		var changeEvent bson.M
		if err := changeStream.Decode(&changeEvent); err != nil {
			log.Fatal(err)
		}

		fmt.Printf("检测到更改: %+v\n", changeEvent)
	}

	if err := changeStream.Err(); err != nil {
		log.Fatal(err)
	}
}

pub端代码

package main

import (
    "context"
    "fmt"
    "time"

    "go.mongodb.org/mongo-driver/bson"
    "go.mongodb.org/mongo-driver/mongo"
    "go.mongodb.org/mongo-driver/mongo/options"
)

func main() {
    // 设置 MongoDB 客户端
    clientOptions := options.Client().ApplyURI("mongodb://localhost:27017")
    client, err := mongo.Connect(context.TODO(), clientOptions)
    if err != nil {
        fmt.Println("连接 MongoDB 失败:", err)
        return
    }
    defer client.Disconnect(context.TODO())

    // 获取数据库和集合
    collection := client.Database("testdb").Collection("items")

    // 插入数据
    for i := 1; i <= 5; i++ {
        item := bson.D{{"name", fmt.Sprintf("item%d", i)}, {"value", i}}
        _, err := collection.InsertOne(context.TODO(), item)
        if err != nil {
            fmt.Println("插入数据失败:", err)
            return
        }
        //fmt.Printf("插入数据: %+v\n", item)
        fmt.Printf("插入数据第 %d 条", i)
        time.Sleep(2 * time.Second) // 模拟一些延迟
    }
}

执行结果 pub端

执行结果 sub端

数据库不用新建集合，自动生成很方便

下面是windows下安装副本集步骤一字不拉

https://www.mongodb.com/try/download/community  下载zip包解压 bin目录同级创建data-data4(data内部需要创建好db目录）,log-log4 
MongoDB shell version v5.0.28  
注意 data目录下没有db文件夹net start MongoDB执行服务起不来   192.168.2.6  本机ip
mongod.exe --config "E:\mongodb\mongod.conf" --serviceName "MongoDB"  --serviceDisplayName "MongoDB"  --install

mongod.exe --config "E:\mongodb\mongod1.conf" --serviceName "MongoDB1"  --serviceDisplayName "MongoDB1"  --install

mongod.exe --config "E:\mongodb\mongod2.conf" --serviceName "MongoDB2"  --serviceDisplayName "MongoDB2"  --install

mongod.exe --config "E:\mongodb\mongod3.conf" --serviceName "MongoDB3"  --serviceDisplayName "MongoDB3"  --install


net start MongoDB
net start MongoDB1
net start MongoDB2
net start MongoDB3

bin目录下打开cmd执行mongo.exe 

rs_conf={_id:"rs",
members:[
{_id:0,host:"192.168.2.6:27017",priority:1}, 
{_id:1,host:"192.168.2.6:27018",priority:2}, 
{_id:2,host:"192.168.2.6:27019",priority:3}, 
{_id:4,host:"192.168.2.6:27020", arbiterOnly:true}
]}

返回这个代表成功:
{
        "_id" : "rs",
        "members" : [
                {
                        "_id" : 0,
                        "host" : "192.168.2.6:27017",
                        "priority" : 1
                },
                {
                        "_id" : 1,
                        "host" : "192.168.2.6:27018",
                        "priority" : 2
                },
                {
                        "_id" : 2,
                        "host" : "192.168.2.6:27019",
                        "priority" : 3
                },
                {
                        "_id" : 4,
                        "host" : "192.168.2.6:27020",
                        "arbiterOnly" : true
                }
        ]
}

rs.initiate(rs_conf)  执行配置
{"ok":1}
rs.status() 查看状态
{
        "set" : "rs",
        "date" : ISODate("2024-08-10T02:40:20.391Z"),
        "myState" : 2,
        "term" : NumberLong(2),
        "syncSourceHost" : "192.168.2.6:27019",
        "syncSourceId" : 2,
        "heartbeatIntervalMillis" : NumberLong(2000),
        "majorityVoteCount" : 3,
        "writeMajorityCount" : 3,
        "votingMembersCount" : 4,
        "writableVotingMembersCount" : 3,
        "optimes" : {
                "lastCommittedOpTime" : {
                        "ts" : Timestamp(1723257616, 1),
                        "t" : NumberLong(2)
                },
                "lastCommittedWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                "readConcernMajorityOpTime" : {
                        "ts" : Timestamp(1723257616, 1),
                        "t" : NumberLong(2)
                },
                "appliedOpTime" : {
                        "ts" : Timestamp(1723257616, 1),
                        "t" : NumberLong(2)
                },
                "durableOpTime" : {
                        "ts" : Timestamp(1723257616, 1),
                        "t" : NumberLong(2)
                },
                "lastAppliedWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                "lastDurableWallTime" : ISODate("2024-08-10T02:40:16.003Z")
        },
        "lastStableRecoveryTimestamp" : Timestamp(1723257586, 1),
        "electionParticipantMetrics" : {
                "votedForCandidate" : true,
                "electionTerm" : NumberLong(2),
                "lastVoteDate" : ISODate("2024-08-10T02:39:15.909Z"),
                "electionCandidateMemberId" : 2,
                "voteReason" : "",
                "lastAppliedOpTimeAtElection" : {
                        "ts" : Timestamp(1723257547, 5),
                        "t" : NumberLong(1)
                },
                "maxAppliedOpTimeInSet" : {
                        "ts" : Timestamp(1723257547, 5),
                        "t" : NumberLong(1)
                },
                "priorityAtElection" : 1,
                "newTermStartDate" : ISODate("2024-08-10T02:39:15.997Z"),
                "newTermAppliedDate" : ISODate("2024-08-10T02:39:16.928Z")
        },
        "members" : [
                {
                        "_id" : 0,
                        "name" : "192.168.2.6:27017",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 2677,
                        "optime" : {
                                "ts" : Timestamp(1723257616, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDate" : ISODate("2024-08-10T02:40:16Z"),
                        "lastAppliedWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                        "lastDurableWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                        "syncSourceHost" : "192.168.2.6:27019",
                        "syncSourceId" : 2,
                        "infoMessage" : "",
                        "configVersion" : 1,
                        "configTerm" : 2,
                        "self" : true,
                        "lastHeartbeatMessage" : ""
                },
                {
                        "_id" : 1,
                        "name" : "192.168.2.6:27018",
                        "health" : 1,
                        "state" : 2,
                        "stateStr" : "SECONDARY",
                        "uptime" : 85,
                        "optime" : {
                                "ts" : Timestamp(1723257616, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDurable" : {
                                "ts" : Timestamp(1723257616, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDate" : ISODate("2024-08-10T02:40:16Z"),
                        "optimeDurableDate" : ISODate("2024-08-10T02:40:16Z"),
                        "lastAppliedWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                        "lastDurableWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                        "lastHeartbeat" : ISODate("2024-08-10T02:40:19.059Z"),
                        "lastHeartbeatRecv" : ISODate("2024-08-10T02:40:20.083Z"),
                        "pingMs" : NumberLong(0),
                        "lastHeartbeatMessage" : "",
                        "syncSourceHost" : "192.168.2.6:27017",
                        "syncSourceId" : 0,
                        "infoMessage" : "",
                        "configVersion" : 1,
                        "configTerm" : 2
                },
                {
                        "_id" : 2,
                        "name" : "192.168.2.6:27019",
                        "health" : 1,
                        "state" : 1,
                        "stateStr" : "PRIMARY",
                        "uptime" : 85,
                        "optime" : {
                                "ts" : Timestamp(1723257616, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDurable" : {
                                "ts" : Timestamp(1723257616, 1),
                                "t" : NumberLong(2)
                        },
                        "optimeDate" : ISODate("2024-08-10T02:40:16Z"),
                        "optimeDurableDate" : ISODate("2024-08-10T02:40:16Z"),
                        "lastAppliedWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                        "lastDurableWallTime" : ISODate("2024-08-10T02:40:16.003Z"),
                        "lastHeartbeat" : ISODate("2024-08-10T02:40:19.060Z"),
                        "lastHeartbeatRecv" : ISODate("2024-08-10T02:40:20.022Z"),
                        "pingMs" : NumberLong(0),
                        "lastHeartbeatMessage" : "",
                        "syncSourceHost" : "",
                        "syncSourceId" : -1,
                        "infoMessage" : "",
                        "electionTime" : Timestamp(1723257555, 1),
                        "electionDate" : ISODate("2024-08-10T02:39:15Z"),
                        "configVersion" : 1,
                        "configTerm" : 2
                },
                {
                        "_id" : 4,
                        "name" : "192.168.2.6:27020",
                        "health" : 1,
                        "state" : 7,
                        "stateStr" : "ARBITER",
                        "uptime" : 85,
                        "lastHeartbeat" : ISODate("2024-08-10T02:40:19.059Z"),
                        "lastHeartbeatRecv" : ISODate("2024-08-10T02:40:20.092Z"),
                        "pingMs" : NumberLong(0),
                        "lastHeartbeatMessage" : "",
                        "syncSourceHost" : "",
                        "syncSourceId" : -1,
                        "infoMessage" : "",
                        "configVersion" : 1,
                        "configTerm" : 2
                }
        ],
        "ok" : 1,
        "$clusterTime" : {
                "clusterTime" : Timestamp(1723257616, 1),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        },
        "operationTime" : Timestamp(1723257616, 1)
}

demo代码链接

go/mongochangestreamsdemo/demo at main · liuzhixin405/go (github.com)

mongo配置链接

config/mongo windows集群 at main · liuzhixin405/config (github.com)

备注: c#代码监听数据库变化需要连接副本 "Connection": "mongodb://localhost:27017,localhost:27018,localhost:27019"，只27017不会获得更新数据。具体原因可能是封装类库有关，暂没有深究。

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