M202 - week 5

Mongo Shading

> mongo --nodb
> config = { shard0 : { smallfiles : "", noprealloc : "", nopreallocj : ""}, shard1 : { smallfiles : "", noprealloc : "", nopreallocj : "" }, shard2 : { smallfiles : "", noprealloc : "", nopreallocj : ""}};

{
	"shard0" : {
		"smallfiles" : "",
		"noprealloc" : "",
		"nopreallocj" : ""
	},
	"shard1" : {
		"smallfiles" : "",
		"noprealloc" : "",
		"nopreallocj" : ""
	},
	"shard2" : {
		"smallfiles" : "",
		"noprealloc" : "",
		"nopreallocj" : ""
	}

> cluster = new ShardingTest( { shards : config ,  other : {manualAddShard:true}} );
.... processes start
... ps -aux command results


Then, start a new mongo shell

> mongo --port 30999

mongos> db.adminCommand({ addShard: "localhost:30000", name: "shard0" });
mongos> db.adminCommand({ addShard: "localhost:30001", name: "shard1" });
mongos> db.adminCommand({ addShard: "localhost:30002", name: "shard2" });

mongos> sh.enableSharding("m202")
mongos> sh.status(true)
mongos> sh.stopBalancer()

mongos> db.adminCommand({split : "m202.presplit", middle : { a : 0 }})
... add other splits (chunks)
mongos> sh.status(true)

m202@m202-ubuntu1404:~$ mongo --port 30999
MongoDB shell version: 2.6.4
connecting to: 127.0.0.1:30999/test
mongos> sh.status()
--- Sharding Status --- 
  sharding version: {
	"_id" : 1,
	"version" : 4,
	"minCompatibleVersion" : 4,
	"currentVersion" : 5,
	"clusterId" : ObjectId("5535858fdf17a2b7969aa268")
}
  shards:
	{  "_id" : "shard0",  "host" : "localhost:30000" }
	{  "_id" : "shard1",  "host" : "localhost:30001" }
	{  "_id" : "shard2",  "host" : "localhost:30002" }
  databases:
	{  "_id" : "admin",  "partitioned" : false,  "primary" : "config" }
	{  "_id" : "test",  "partitioned" : false,  "primary" : "shard1" }
	{  "_id" : "m202",  "partitioned" : true,  "primary" : "shard1" }
		m202.presplit
			shard key: { "a" : 1 }
			chunks:
				shard1	4
				shard0	3
				shard2	4
			{ "a" : { "$minKey" : 1 } } -->> { "a" : 0 } on : shard1 Timestamp(9, 1) 
			{ "a" : 0 } -->> { "a" : 7 } on : shard0 Timestamp(11, 1) 
			{ "a" : 7 } -->> { "a" : 10 } on : shard0 Timestamp(3, 0) 
			{ "a" : 10 } -->> { "a" : 14 } on : shard0 Timestamp(10, 0) 
			{ "a" : 14 } -->> { "a" : 15 } on : shard1 Timestamp(11, 0) 
			{ "a" : 15 } -->> { "a" : 20 } on : shard1 Timestamp(1, 11) 
			{ "a" : 20 } -->> { "a" : 21 } on : shard1 Timestamp(1, 13) 
			{ "a" : 21 } -->> { "a" : 22 } on : shard2 Timestamp(10, 1) 
			{ "a" : 22 } -->> { "a" : 23 } on : shard2 Timestamp(6, 0) 
			{ "a" : 23 } -->> { "a" : 24 } on : shard2 Timestamp(7, 0) 
			{ "a" : 24 } -->> { "a" : { "$maxKey" : 1 } } on : shard2 Timestamp(8, 0) 

... move chunks if necessary
mongos> sh.moveChunk("m202.presplit", {"a": 14}, "shard1")

... done