MongoDB 分片（sharding）
🏷️ MongoDB
按值的范围进行横向分片，简称分片（sharding）
创建两个 mongo 服务器并分别启动；
bash
cd /mongodb/
mkdir ./mongo4 ./mongo5
cd /mongodb/
./bin/mongod --shardsvr --dbpath ./mongo4 --port 27014
cd /mongodb/
./bin/mongod --shardsvr --dbpath ./mongo5 --port 27015创建一个 config（配置）服务器；
bash
cd /mongodb/
mkdir ./mongoconfig
./bin/mongod --configsvr --dbpath ./mongoconfig --port 27016创建一个 mongos 服务器，它是对客户的一个单点入口；
bash
cd /mongodb/
./bin/mongos --configdb localhost:27016 --chunkSize 1 --port 27020连接 mongos 服务器，进入 admin 数据库并配置分片；
bash
[liujj@localhost ~]$ cd /mongodb/
[liujj@localhost mongodb]$ ./bin/mongo localhost:27020/admin
MongoDB shell version: 3.2.4
connecting to: localhost:27020/admin
mongos> db.runCommand( { addshard : "localhost:27014" } )
{ "shardAdded" : "shard0000", "ok" : 1 }
mongos> db.runCommand( { addshard : "localhost:27015" } )
{ "shardAdded" : "shard0001", "ok" : 1 }
mongos> db.runCommand( { enablesharding : "test" } )
{ "ok" : 1 }
mongos> db.runCommand( { shardcollection : "test.cities", key : {name : 1} } )
{ "collectionsharded" : "test.cities", "ok" : 1 }
mongos>从 json 文件导入 cities 数据；
bash
[liujj@localhost ~]$ cd /mongodb/
[liujj@localhost mongodb]$ ./bin/mongoimport -h localhost:27020 --db test --collection cities --type json /mongodb/scripts/mongo_cities1000.json
2016-04-07T07:07:29.561-0700 connected to: localhost:27020
2016-04-07T07:07:32.420-0700 [#######.................] test.cities 3.7 MB/12.3 MB (30.1%)
2016-04-07T07:07:35.419-0700 [############............] test.cities 6.3 MB/12.3 MB (50.7%)
2016-04-07T07:07:38.423-0700 [################........] test.cities 8.6 MB/12.3 MB (69.7%)
2016-04-07T07:07:41.434-0700 [####################....] test.cities 10.7 MB/12.3 MB (86.4%)
2016-04-07T07:07:44.105-0700 [########################] test.cities 12.3 MB/12.3 MB (100.0%)
2016-04-07T07:07:44.105-0700 imported 99838 documents
[liujj@localhost mongodb]$分别连接两个分片服务器并统计 name 的第一个字符，看看分别存储了哪些数据及数据件数；
点击查看统计结果
bash
localhost:27014
[liujj@localhost mongodb]$ ./bin/mongo localhost:27014
MongoDB shell version: 3.2.4
connecting to: localhost:27014/test
> db.cities.group({
... initial: { names: {} },
... reduce: function(city, output) {
... output.names[city.name.substr(0,1)] = 1;
... },
... finalize: function (out) {
... var ary = ;
... for(var p in out.names) { ary.push(p); }
... out.names = ary;
... }
... })
[
{
"names" : [
"S",
"P",
"O",
"l",
"U",
"R",
"M",
"`",
"T",
"Z",
"Y",
"Q",
"N",
"L",
"Ḩ",
"Ā",
"Ç",
"V",
"W",
"İ",
"X",
"Ş",
"Ə",
"Ž",
"Š",
"Č",
"Ć",
"É",
"Á",
"v",
"О",
"Ü",
"Í",
"Ú",
"Ř",
"Ö",
"‘",
"Ø",
"Å",
"e",
"Ţ",
"Ṭ",
"Ó",
"s",
"Ò",
"Ä",
"Œ",
"È",
"h",
"Ý",
"Μ",
"Ő",
"d",
"Ẕ",
"m",
"Ḥ",
"Ū",
"k",
"p",
"Ī",
"Þ",
"Ō",
"Ŭ",
"Ķ",
"Ж",
"З",
"В",
"Т",
"С",
"Ш",
"Р",
"П",
"Н",
"М",
"Л",
"К",
"Ј",
"И",
"Г",
"Д",
"Ч",
"Ц",
"Б",
"А",
"Ż",
"Ħ",
"f",
"Ñ",
"Ś",
"Ł",
"Î",
"b",
"Ð",
"Ḑ",
"Ľ",
"ك",
"g"
]
}
]
> db.cities.count()
54150
localhost:27015
[liujj@localhost mongodb]$ ./bin/mongo localhost:27015
MongoDB shell version: 3.2.4
connecting to: localhost:27015/test
> db.cities.group({
... initial: { names: {} },
... reduce: function(city, output) {
... output.names[city.name.substr(0,1)] = 1;
... },
... finalize: function (out) {
... var ary = ;
... for(var p in out.names) { ary.push(p); }
... out.names = ary;
... }
... })
[
{
"names" : [
"‘",
"城",
"东",
"’",
"A",
"B",
"E",
"C",
"D",
"연",
"옥",
"진",
"'",
"F",
"H",
"G",
"K",
"J",
"I",
"L"
]
}
]
> db.cities.count()
45688可以看出数据差不多平均分布在两个服务器上，而且开头的字母都不相同。