Sharding in MongoDB

Horizontal scaling

Method of storing data across multiple m/c

Shards stores user related data

• Start Server service

mongod --configsvr --dbpath C:\data\confdb --port 27019

• Start  Agent service

mongos --configdb localhost:27019

• Start  Database server

mongod --dbpath C:\data\sh1 --port 27020

• Start Client

C:\>mongo --host localhost --port 27017

MongoDB shell version: 2.6.5

connecting to: localhost:27017/test

mongos>

mongos> sh.status()

--- Sharding Status ---

  sharding version: {

        "_id" : 1,

        "version" : 4,

        "minCompatibleVersion" : 4,

        "currentVersion" : 5,

        "clusterId" : ObjectId("55936ac576a153b4e1f67c45")

}

  shards:

  databases:

        {  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }

• Adding shard

mongos> sh.addShard("localhost:27020")

{ "shardAdded" : "shard0000", "ok" : 1 }

• Check status again

mongos> sh.status()

--- Sharding Status ---

  sharding version: {

        "_id" : 1,

        "version" : 4,

        "minCompatibleVersion" : 4,

        "currentVersion" : 5,

        "clusterId" : ObjectId("55936ac576a153b4e1f67c45")

}

  shards:

        {  "_id" : "shard0000",  "host" : "localhost:27020" }

  databases:

        {  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }

Enable sharding

mongos> use mydb1

switched to db mydb1

mongos> sh.enableSharding("mydb1")

{ "ok" : 1 }

mongos> db.createCollection("shTbl")

{ "ok" : 1 }

mongos> db.shTbl.insert({x:1})

WriteResult({ "nInserted" : 1 })

mongos> db.shTbl.find()

{ "_id" : ObjectId("55936e5fc7deef0077d13a9c"), "x" : 1 }

mongos> sh.status()

--- Sharding Status ---

  sharding version: {

        "_id" : 1,

        "version" : 4,

        "minCompatibleVersion" : 4,

        "currentVersion" : 5,

        "clusterId" : ObjectId("55936ac576a153b4e1f67c45")

}

  shards:

        {  "_id" : "shard0000",  "host" : "localhost:27020" }

  databases:

        {  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }

        {  "_id" : "mydb1",  "partitioned" : true,  "primary" : "shard0000" }

mongos> db.shTbl.ensureIndex({x:1})

{

        "raw" : {

                "localhost:27020" : {

                        "createdCollectionAutomatically" : false,

                        "numIndexesBefore" : 1,

                        "numIndexesAfter" : 2,

                        "ok" : 1

                }

        },

        "ok" : 1

}

mongos> db.shTbl.getIndexex()

2015-07-01T10:09:05.018+0530 TypeError: Property 'getIndexex' of object mydb1.shTbl is not a functi

mongos> db.shTbl.getIndexes()

[

        {

                "v" : 1,

                "key" : {

                        "_id" : 1

                },

                "name" : "_id_",

                "ns" : "mydb1.shTbl"

        },

        {

                "v" : 1,

                "key" : {

                        "x" : 1

                },

                "name" : "x_1",

                "ns" : "mydb1.shTbl"

        }

]

mongos> sh.shardCollection("mydb1.shTbl",{"x":1})

{ "collectionsharded" : "mydb1.shTbl", "ok" : 1 }

mongos>

mongos> sh.status()

--- Sharding Status ---

  sharding version: {

        "_id" : 1,

        "version" : 4,

        "minCompatibleVersion" : 4,

        "currentVersion" : 5,

        "clusterId" : ObjectId("55936ac576a153b4e1f67c45")

}

  shards:

        {  "_id" : "shard0000",  "host" : "localhost:27020" }

  databases:

        {  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }

        {  "_id" : "mydb1",  "partitioned" : true,  "primary" : "shard0000" }

                mydb1.shTbl

                        shard key: { "x" : 1 }

                        chunks:

                                shard0000       1

                        { "x" : { "$minKey" : 1 } } -->> { "x" : { "$maxKey" : 1 } } on : shard0000 Timestamp(1,

)

mongos>

mongos> db.shTbl.insert({x:2})

WriteResult({ "nInserted" : 1 })

mongos> db.shTbl.insert({x:3})

WriteResult({ "nInserted" : 1 })

mongos> db.shTbl.insert({x:4})

WriteResult({ "nInserted" : 1 })

mongos>

mongos> sh.status()

--- Sharding Status ---

  sharding version: {

        "_id" : 1,

        "version" : 4,

        "minCompatibleVersion" : 4,

        "currentVersion" : 5,

        "clusterId" : ObjectId("55936ac576a153b4e1f67c45")

}

  shards:

        {  "_id" : "shard0000",  "host" : "localhost:27020" }

  databases:

        {  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }

        {  "_id" : "mydb1",  "partitioned" : true,  "primary" : "shard0000" }

                mydb1.shTbl

                        shard key: { "x" : 1 }

                        chunks:

                                shard0000       1

                        { "x" : { "$minKey" : 1 } } -->> { "x" : { "$maxKey" : 1 } } on : shard0000 Timestamp(1,

)

mongos> db.shTbl.find()

{ "_id" : ObjectId("55936e5fc7deef0077d13a9c"), "x" : 1 }

{ "_id" : ObjectId("55936facc7deef0077d13a9d"), "x" : 2 }

{ "_id" : ObjectId("55936fb7c7deef0077d13a9e"), "x" : 3 }

{ "_id" : ObjectId("55936fbec7deef0077d13a9f"), "x" : 4 }

mongos>

Test the sharding by connecting to sharded client of port 27020

C:\>mongo --port 27020

MongoDB shell version: 2.6.5

connecting to: 127.0.0.1:27020/test

> show dbs

admin  (empty)

local  0.078GB

mydb1  0.078GB

> use mydb1

switched to db mydb1

> show collections

shTbl

system.indexes

> db.shTbl.find()

{ "_id" : ObjectId("55936e5fc7deef0077d13a9c"), "x" : 1 }

{ "_id" : ObjectId("55936facc7deef0077d13a9d"), "x" : 2 }

{ "_id" : ObjectId("55936fb7c7deef0077d13a9e"), "x" : 3 }

{ "_id" : ObjectId("55936fbec7deef0077d13a9f"), "x" : 4 }

>