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 localswitched to db localhandong1:PRIMARY> db.oplog.rs.stats().maxSizeNumberLong("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 localswitched to db localhandong1:SECONDARY> db.oplog.rs.stats().maxSizeNumberLong("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().maxSizeNumberLong(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 localswitched to db localhandong1:PRIMARY> handong1:PRIMARY> db.oplog.rs.stats().maxSizeNumberLong("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().maxSizeNumberLong(2097152000)

能够看到primary节点oplog大小也批改为了2000MB。