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)