关于mongodb:Mongodb在线修改oplog大小

MongoDB 3.6开始，能够应用命令replSetResizeOplog批改正本集成员的oplog大小，从secondary节点开始批改，而后顺次到主节点。本文测试环境为MongoDB 4.2。

能够通过命令查看oplog大小

handong1:PRIMARY> use local
switched to db local
handong1:PRIMARY> db.oplog.rs.stats().maxSize
NumberLong("5242880000")

maxSize字段以字节为单位显示汇合大小，能够看到以后节点oplog大小为5242880000/1024/1024=5000MB。

接下来咱们批改正本集（一主一从一仲裁）各个成员的oplog大小。
先批改secondary节点的oplog大小。

handong1:SECONDARY> use local
switched to db local
handong1:SECONDARY> db.oplog.rs.stats().maxSize
NumberLong("10485760000")
handong1:SECONDARY> db.adminCommand({replSetResizeOplog: 1, size: 2000})
{
    "ok" : 1,
    "$clusterTime" : {
        "clusterTime" : Timestamp(1617786418, 1),
        "signature" : {
            "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
            "keyId" : NumberLong(0)
        }
    },
    "operationTime" : Timestamp(1617786418, 1)
}
handong1:SECONDARY> db.oplog.rs.stats().maxSize
NumberLong(2097152000)

secondary节点oplog大小改为了2000MB。

而后批改primary节点的oplog大小。

handong1:PRIMARY> use local
switched to db local
handong1:PRIMARY> 
handong1:PRIMARY> db.oplog.rs.stats().maxSize
NumberLong("5242880000")
handong1:PRIMARY> db.adminCommand({replSetResizeOplog: 1, size: 2000})
{
    "ok" : 1,
    "$clusterTime" : {
        "clusterTime" : Timestamp(1617786579, 1),
        "signature" : {
            "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
            "keyId" : NumberLong(0)
        }
    },
    "operationTime" : Timestamp(1617786579, 1)
}
handong1:PRIMARY> db.oplog.rs.stats().maxSize
NumberLong(2097152000)

能够看到primary节点oplog大小也批改为了2000MB。