手动分片的操作

自动分片会带来性能的下降. 所以要合理使用手动分片. 并且配合Tag一起使用.

# 对于4个shard的程序, 预先处理的指令
1. 加入分片服务器
sh.addShard( "192.168.1.60:27017" )
sh.addShard( "192.168.1.61:27017" )
sh.addShard( "192.168.1.62:27017" )
sh.addShard( "192.168.1.63:27017" )

2. 启动collection分片, 并指定分片键
db.location.ensureIndex({"hostid":1})
sh.enableSharding("mydb")
sh.shardCollection("mydb.location", { "hostid": 1})

运行 sh.status()

{ "_id" : "mydb", "partitioned" : true, "primary" : "shard0003" }
mydb.location
shard key: { "hostid" : 1 }
chunks:
shard0003 1
{ "hostid" : { "$minKey" : 1 } } -->> { "hostid" : { "$maxKey" : 1 } } on : shard0003 Timestamp(1, 0)

sh.addShardTag("shard0000", "TAG0")
sh.addShardTag("shard0001", "TAG1")
sh.addShardTag("shard0002", "TAG2")
sh.addShardTag("shard0003", "TAG3")

# 具体操作
1. 加入tagrange,
加入两个
sh.addTagRange("mydb.location", { hostid: "0000000" }, { hostid: "3100000" }, "TAG0")
sh.addTagRange("mydb.location", { hostid: "3100000" }, { hostid: "3200000" }, "TAG1")

由于当前的primary位 shard0003,
sh.addTagRange("mydb.location", { hostid: "3200000" }, { hostid: "3300000" }, "TAG2")
sh.addTagRange("mydb.location", { hostid: "3300000" }, { hostid: "3500000" }, "TAG3")
sh.addTagRange("mydb.location", { hostid: "3500000" }, { $maxKey: 1 }, "TAG3")

4. add chunck
// 将primary 放到第二个分片上
db.runCommand({movePrimary:"mydb",to:"shard0001"})
查看分片情况
db.chunks.find({ns:"mydb.location"})

手动建立空的chunk
for ( var x=300; x<350; x++ ){
var prefix = String(x*10000);
sh.splitAt( "mydb.location", { "hostid":prefix } )
}

然后移动chunk到对应的地方, 移动chunk的命令
sh.moveChunk("mydb.location", { hostid: "3000000"}, "shard0000")

==shard0000
for ( var x=300; x<310; x++ ){
var prefix = String(x*10000);
sh.moveChunk( "mydb.location", { "hostid":prefix }, "shard0000" )
}

==shard0001 310 - 320
==shard0002 320 - 330
==shard0003 330 - 350

其他一些查询操作
// 查找大于 340000的数据, 并且
db.chunks.find({ns:"mydb.location", min:{$gte:{ "hostid" : "3400000" }}})

db.getSiblingDB("admin").runCommand( { moveChunk : "mydb.location" ,
find : { "hostid" : "3400000" } ,
to : "shard0003" } )

1. 建立索引
use mydb
db.location.ensureIndex({"hostid":1})
db.location.ensureIndex({"posTime":1})
db.location.ensureIndex({"hostno":1})
db.location.createIndex( { loc : "2dsphere" } )

db.location.ensureIndex({"posTime":1,"loc":"2dsphere"})
db.location.ensureIndex({"posTime":1,"hostno":1,"loc":"2dsphere"})
db.location.getIndexes()

mongodb 手动分片的命令汇总