查看oplog使用情况和修改oplog大小

环境:
OS:Centos 7
db:4.4.22

1.查看当前的大小

myrepl:PRIMARY> db.getReplicationInfo()
{
        "logSizeMB" : 10000,
        "usedMB" : 10013.92,
        "timeDiff" : 7801,
        "timeDiffHours" : 2.17,
        "tFirst" : "Fri Jul 14 2023 00:20:39 GMT-0400 (EDT)",
        "tLast" : "Fri Jul 14 2023 02:30:40 GMT-0400 (EDT)",
        "now" : "Fri Jul 14 2023 02:30:41 GMT-0400 (EDT)"
}

或是
myrepl:PRIMARY> use local
switched to db local
myrepl:PRIMARY> db.oplog.rs.stats().maxSize
NumberLong("10485760000")

我这里的大小是10GB,下面调整为1GB

2.修改oplog.rs大小
执行顺序:从节点-->主节点
myrepl:SECONDARY> use local
myrepl:SECONDARY> db.adminCommand({replSetResizeOplog:1, size: 1024});
{ "ok" : 1 }

myrepl:PRIMARY> use local
myrepl:PRIMARY> db.adminCommand({replSetResizeOplog:1, size: 1024});
{ "ok" : 1 }

仲裁节点不需要执行.

3.回收空间
从库
myrepl:SECONDARY> use local
myrepl:SECONDARY> db.runCommand({ "compact" : "oplog.rs" })

主库:
myrepl:PRIMARY> use local
myrepl:PRIMARY> db.runCommand({ "compact" : "oplog.rs",force:true })

主库执行需要加上force:true参数

4.重启是否失效
关闭顺序:仲裁节点-->从节点-->主节点
/usr/local/services/mongodb/bin/mongo localhost:29001
use admin
db.auth("test","test123"); ##仲裁节点不需要
db.shutdownServer()

启动
启动顺序:主节点-->从节点-->仲裁节点
/usr/local/services/mongodb/bin/mongod -f /home/middle/mongodb/conf/mongo.cnf

查看是否失效

/usr/local/services/mongodb/bin/mongo localhost:29001
myrepl:PRIMARY> use admin
myrepl:PRIMARY> db.auth("test","test123");
myrepl:PRIMARY> db.getReplicationInfo()
{
        "logSizeMB" : 1024,
        "usedMB" : 997.76,
        "timeDiff" : 9542,
        "timeDiffHours" : 2.65,
        "tFirst" : "Fri Jul 14 2023 00:29:47 GMT-0400 (EDT)",
        "tLast" : "Fri Jul 14 2023 03:08:49 GMT-0400 (EDT)",
        "now" : "Fri Jul 14 2023 03:08:52 GMT-0400 (EDT)"
}