在 MongoDB 中，查看副本集成员之间的副本延迟可以通过以下步骤进行：
-
使用
rs.status()命令：
这个命令提供了副本集的详细状态信息，包括每个成员的延迟情况。在 MongoDB shell 中，你可以执行以下命令：rs.status()这个命令会返回一个包含副本集所有成员状态的对象。在返回的对象中，每个成员都有一个
optime字段，显示了该成员最后应用的操作的时间戳。 -
查看
optime字段：
optime字段是一个包含两个部分的对象：ts（timestamp）和t（term）。ts是一个 Timestamp 对象，表示最后应用的操作的时间。 -
比较主节点和从节点的
optime：
主节点的optime应该总是最新的，而从节点的optime可能会有所延迟。你可以通过比较主节点和从节点的optime来估计延迟。 -
使用
rs.printReplicationInfo()命令：
这个命令提供了一个更易于阅读的副本集状态报告，包括每个成员的延迟信息。在 MongoDB shell 中，执行以下命令：rs.printReplicationInfo()这个命令会打印出副本集的状态信息，包括每个成员的延迟。
-
监控延迟：
如果你想要持续监控副本集的延迟，你可以定期运行这些命令，或者使用 MongoDB 的监控工具，如 MongoDB Cloud Manager 或第三方监控解决方案。
请注意，副本延迟可能会因为网络延迟、磁盘 I/O、CPU 使用率等因素而变化。如果你发现延迟异常高，可能需要检查副本集成员的性能和配置。
mongo-baa26600-replica0:SECONDARY> rs.printReplicationInfo()
configured oplog size: 10240MB
log length start to end: 370018secs (102.78hrs)
oplog first event time: Fri Sep 06 2024 10:54:09 GMT+0800 (CST)
oplog last event time: Tue Sep 10 2024 17:41:07 GMT+0800 (CST)
now: Tue Sep 10 2024 17:41:14 GMT+0800 (CST)
mongo-baa26600-replica0:SECONDARY> rs.status()
{
"set" : "mongo-baa26600-replica0",
"date" : ISODate("2024-09-10T09:42:31.340Z"),
"myState" : 2,
"term" : NumberLong(162),
"syncSourceHost" : "10.10.98.127:3692",
"syncSourceId" : 2,
"heartbeatIntervalMillis" : NumberLong(2000),
"majorityVoteCount" : 2,
"writeMajorityCount" : 2,
"votingMembersCount" : 3,
"writableVotingMembersCount" : 3,
"optimes" : {
"lastCommittedOpTime" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"lastCommittedWallTime" : ISODate("2024-09-10T09:42:26.430Z"),
"readConcernMajorityOpTime" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"readConcernMajorityWallTime" : ISODate("2024-09-10T09:42:26.430Z"),
"appliedOpTime" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"durableOpTime" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"lastAppliedWallTime" : ISODate("2024-09-10T09:42:26.430Z"),
"lastDurableWallTime" : ISODate("2024-09-10T09:42:26.430Z")
},
"electionParticipantMetrics" : {
"votedForCandidate" : true,
"electionTerm" : NumberLong(162),
"lastVoteDate" : ISODate("2024-09-10T08:55:47.309Z"),
"electionCandidateMemberId" : 2,
"voteReason" : "",
"lastAppliedOpTimeAtElection" : {
"ts" : Timestamp(1725958536, 1),
"t" : NumberLong(161)
},
"maxAppliedOpTimeInSet" : {
"ts" : Timestamp(1725958536, 1),
"t" : NumberLong(161)
},
"priorityAtElection" : 1,
"newTermStartDate" : ISODate("2024-09-10T08:55:47.311Z"),
"newTermAppliedDate" : ISODate("2024-09-10T08:55:48.546Z")
},
"members" : [
{
"_id" : 0,
"name" : "10.10.98.123:7315",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 4539,
"optime" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"optimeDurable" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"optimeDate" : ISODate("2024-09-10T09:42:26Z"),
"optimeDurableDate" : ISODate("2024-09-10T09:42:26Z"),
"lastHeartbeat" : ISODate("2024-09-10T09:42:30.831Z"),
"lastHeartbeatRecv" : ISODate("2024-09-10T09:42:30.318Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncSourceHost" : "10.10.98.127:3692",
"syncSourceId" : 2,
"infoMessage" : "",
"configVersion" : 111017,
"configTerm" : -1
},
{
"_id" : 1,
"name" : "10.10.98.125:4933",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 86381,
"optime" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"optimeDate" : ISODate("2024-09-10T09:42:26Z"),
"syncSourceHost" : "10.10.98.127:3692",
"syncSourceId" : 2,
"infoMessage" : "",
"configVersion" : 111017,
"configTerm" : -1,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 2,
"name" : "10.10.98.127:3692",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 86378,
"optime" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"optimeDurable" : {
"ts" : Timestamp(1725961346, 1),
"t" : NumberLong(162)
},
"optimeDate" : ISODate("2024-09-10T09:42:26Z"),
"optimeDurableDate" : ISODate("2024-09-10T09:42:26Z"),
"lastHeartbeat" : ISODate("2024-09-10T09:42:30.830Z"),
"lastHeartbeatRecv" : ISODate("2024-09-10T09:42:31.332Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1725958547, 1),
"electionDate" : ISODate("2024-09-10T08:55:47Z"),
"configVersion" : 111017,
"configTerm" : -1
}
],
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1725961346, 1),
"signature" : {
"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
"keyId" : NumberLong(0)
}
},
"operationTime" : Timestamp(1725961346, 1)
}