MongoDB整理笔记の管理Sharding

    1、列出所有的Shard Server

> db.runCommand({ listshards: 1 }) --列出所有的Shard Server
{
"shards" : [
{
"_id" : "shard0000",
"host" : "localhost:20000"
},
{
"_id" : "shard0001",
"host" : "localhost:20001"
}
],
"ok" : 1
}

    2、查看Sharding信息

> printShardingStatus() --查看Sharding 信息
--- Sharding Status ---
sharding version: { "_id" : 1, "version" : 3 }
shards:
{ "_id" : "shard0000", "host" : "localhost:20000" }
{ "_id" : "shard0001", "host" : "localhost:20001" }
databases:
{ "_id" : "admin", "partitioned" : false, "primary" : "config" }
{ "_id" : "test", "partitioned" : true, "primary" : "shard0000" }
test.users chunks:
shard0000 1
{ "_id" : { $minKey : 1 } } -->> { "_id" : { $maxKey : 1 } } on :
shard0000 { "t" : 1000, "i" : 0 }
>

    3、判断是否是Sharding

> db.runCommand({ isdbgrid:1 })
{ "isdbgrid" : 1, "hostname" : "localhost", "ok" : 1 }
>

    4、对现有的集合进行分片（实例）

    刚才我们是对表test.users 进行分片了，下面我们将对库中现有的未分片的表test.users_2 进行分片处理。

    表最初状态如下，可以看出他没有被分片过：

> db.users_2.stats()
{
"ns" : "test.users_2",
"sharded" : false,
"primary" : "shard0000",
"ns" : "test.users_2",
"count" : 500000,
"size" : 48000016,
"avgObjSize" : 96.000032,
"storageSize" : 61875968,
"numExtents" : 11,
"nindexes" : 1,
"lastExtentSize" : 15001856,
"paddingFactor" : 1,
"flags" : 1,
"totalIndexSize" : 20807680,
"indexSizes" : {
"_id_" : 20807680
},
"ok" : 1
}

    对其进行分片处理:

> use admin
switched to db admin
> db.runCommand({ shardcollection: "test.users_2", key: { _id:1 }})
{ "collectionsharded" : "test.users_2", "ok" : 1 }

    再次查看分片后的表的状态，可以看到它已经被我们分片了

> use test
switched to db test
> db.users_2.stats()
{
"sharded" : true,
"ns" : "test.users_2",
"count" : 505462,
……
"shards" : {
"shard0000" : {
"ns" : "test.users_2",
……
"ok" : 1
},
"shard0001" : {
"ns" : "test.users_2",
……
"ok" : 1
}
},
"ok" : 1
}
>