mongodb分片集群管理

config数据库中的集合：

mongos> show dbs
admin     0.000GB
athena  157.194GB
config    0.014GB

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mongos> use config
switched to db config

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mongos> show tables
actionlog
changelog
chunks
collections
databases
lockpings
locks
migrations
mongos
shards
system.profile
tags
transactions
version

查看数据库的默认存储分片（主分片）和支持分片的数据库：

               这个primary与replica set里面的primary不是一回事，这里的primary是primary shard的意思，我们知道即使在sharded cluster环境中，一些数据量比较小的db也是无需分片的，这些db默认就存放在primary shard上面。

mongos> use config

mongos> db.databases.find()
{ "_id" : "athena", "primary" : "bwactivity_shard", "partitioned" : true, "version" : { "uuid" : UUID("d3c927c5-29ee-4d27-b8ad-ac69332d3059"), "lastMod" : 1 } }
mongos> db.databases.find().pretty()
{
        "_id" : "athena",
        "primary" : "bwactivity_shard",
        "partitioned" : true,
        "version" : {
                "uuid" : UUID("d3c927c5-29ee-4d27-b8ad-ac69332d3059"),
                "lastMod" : 1
        }
}

查看分片集群中哪些集合开启了分片和片键：

mongos> db.collections.find().pretty()
{
        "_id" : "config.system.sessions",
        "lastmodEpoch" : ObjectId("5f89496f82b8dec4f83d5506"),
        "lastmod" : ISODate("1970-02-19T17:02:47.296Z"),
        "dropped" : false,
        "key" : {
                "_id" : 1
        },
        "unique" : false,
        "uuid" : UUID("48dfd0fb-7fcd-44dd-bb26-55e09050d60c")
}
{
        "_id" : "athena.athena_user_task_new",
        "lastmodEpoch" : ObjectId("5f8e4c9382b8dec4f808aefb"),
        "lastmod" : ISODate("1970-02-19T17:02:47.299Z"),
        "dropped" : false,
        "key" : {
                "uid" : "hashed"
        },
        "unique" : false,
        "uuid" : UUID("a6bae3e6-4428-4f61-b7a8-30d7a99628e9")
}
{
        "_id" : "athena.athena_user_task_v2",
        "lastmodEpoch" : ObjectId("5fa4e12582b8dec4f8802392"),
        "lastmod" : ISODate("1970-02-19T17:02:47.299Z"),
        "dropped" : false,
        "key" : {
                "uid" : "hashed"
        },
        "unique" : false,
        "uuid" : UUID("d1c674ab-3194-4944-8b49-48e0cd511ea3")
}
{
        "_id" : "athena.athena_user_task_v3",
        "lastmodEpoch" : ObjectId("000000000000000000000000"),
        "lastmod" : ISODate("2020-11-05T06:55:12.147Z"),
        "dropped" : true
}
mongos>

查看分片集群中有哪些分片sharding：

mongos> use config

mongos> db.shards.find().pretty()
{
        "_id" : "bwactivity_shard",
        "host" : "bwactivity_shard/aaa:28001,bbb:28001,ccc:28001",
        "state" : 1
}
{
        "_id" : "bwactivity_shard2",
        "host" : "bwactivity_shard2/xxx:28002,yyy:28002,zzz:28002",
        "state" : 1
}

 查看分片集群有哪些路由mongos：

mongos> db.mongos.find().pretty()
{
        "_id" : "ddd:30000",
        "advisoryHostFQDNs" : [
                "c4-internet3-bwaward-mgdb01.bj"
        ],
        "mongoVersion" : "4.0.14-8",
        "ping" : ISODate("2020-11-11T08:20:27.119Z"),
        "up" : NumberLong(541006),
        "waiting" : true
}
{
        "_id" : "eee:30000",
        "advisoryHostFQDNs" : [
                "c4-internet3-bwaward-mgdb02.bj"
        ],
        "mongoVersion" : "4.0.14-8",
        "ping" : ISODate("2020-11-11T08:20:27.121Z"),
        "up" : NumberLong(541113),
        "waiting" : true
}
{
        "_id" : "fff:30000",
        "advisoryHostFQDNs" : [
                "c4-internet3-bwaward-mgdb03.bj"
        ],
        "mongoVersion" : "4.0.14-8",
        "ping" : ISODate("2020-11-11T08:20:35.613Z"),
        "up" : NumberLong(541052),
        "waiting" : true
}
mongos> 

查看分片集群的分片信息汇总：

mongos> sh.status()
--- Sharding Status --- 
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("5f893d07fe296990bc8a1f50")
  }
  shards:
        {  "_id" : "bwactivity_shard",  "host" : "bwactivity_shard/aaa:28001,bbb:28001,ccc:28001",  "state" : 1 }
        {  "_id" : "bwactivity_shard2",  "host" : "bwactivity_shard2/xxx:28002,yyy:28002,zzz:28002",  "state" : 1 }
  active mongoses:
        "4.0.14-8" : 3
  autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours: 
                41 : Success
                1 : Failed with error 'aborted', from bwactivity_shard to bwactivity_shard2
  databases:
        {  "_id" : "athena",  "primary" : "bwactivity_shard",  "partitioned" : true,  "version" : {  "uuid" : UUID("d3c927c5-29ee-4d27-b8ad-ac69332d3059"),  "lastMod" : 1 } }
                athena.athena_user_task_new
                        shard key: { "uid" : "hashed" }
                        unique: false
                        balancing: true
                        chunks:
                                bwactivity_shard        295
                                bwactivity_shard2       294
                        too many chunks to print, use verbose if you want to force print
                athena.athena_user_task_v2
                        shard key: { "uid" : "hashed" }
                        unique: false
                        balancing: true
                        chunks:
                                bwactivity_shard        1332
                                bwactivity_shard2       1335
                        too many chunks to print, use verbose if you want to force print
        {  "_id" : "config",  "primary" : "config",  "partitioned" : true }
                config.system.sessions
                        shard key: { "_id" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                bwactivity_shard        1
                        { "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : bwactivity_shard Timestamp(1, 0) 

mongos> 

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