View Cluster Configuration¶

On this page

List Databases with Sharding Enabled¶

To list the databases that have sharding enabled, query the databases collection in the Config Database. A database has sharding enabled if the value of the partitioned field is true. Connect to a mongos instance with a mongo shell, and run the following operation to get a full list of databases with sharding enabled:

use config
db.databases.find( { "partitioned": true } )

Example

You can use the following sequence of commands when to return a list of all databases in the cluster:

use config
db.databases.find()

If this returns the following result set:

{ "_id" : "test", "primary" : "shardB", "partitioned" : false }
{ "_id" : "animals", "primary" : "shardA", "partitioned" : true }
{ "_id" : "farms", "primary" : "shardA", "partitioned" : false }

Then sharding is only enabled for the animals database.

List Shards¶

To list the current set of configured shards, use the listShards command, as follows:

db.adminCommand( { listShards : 1 } )

View Cluster Details¶

To view cluster details, issue db.printShardingStatus() or sh.status(). Both methods return the same output.

Example

In the following example output from sh.status()

sharding version displays the version number of the shard metadata.
shards displays a list of the mongod instances used as shards in the cluster.
databases displays all databases in the cluster, including database that do not have sharding enabled.
The chunks information for the foo database displays how many chunks are on each shard and displays the range of each chunk.

--- Sharding Status ---
  sharding version: {
    "_id" : 1,
    "minCompatibleVersion" : 5,
    "currentVersion" : 6,
    "clusterId" : ObjectId("59a4443c3d38cd8a0b40316d")
  }
  shards:
    {  "_id" : "shard0000",  "host" : "m0.example.net:27018" }
    {  "_id" : "shard0001",  "host" : "m3.example2.net:27018" }
    {  "_id" : "shard0002",  "host" : "m2.example.net:27018" }
  active mongoses:
    "3.4.7" : 1
  autosplit:
    Currently enabled: yes
   balancer:
    Currently enabled:  yes
    Currently running:  no
    Failed balancer rounds in last 5 attempts:  0
    Migration Results for the last 24 hours:
       1 : Success
  databases:
    {  "_id" : "foo",  "partitioned" : true,  "primary" : "shard0000" }
        foo.contacts
            shard key: { "zip" : 1 }
            unique: false
            balancing: true
            chunks:
                shard0001    2
                shard0002    3
                shard0000    2
            { "zip" : { "$minKey" : 1 } } -->> { "zip" : "56000" } on : shard0001 { "t" : 2, "i" : 0 }
            { "zip" : 56000 } -->> { "zip" : "56800" } on : shard0002 { "t" : 3, "i" : 4 }
            { "zip" : 56800 } -->> { "zip" : "57088" } on : shard0002 { "t" : 4, "i" : 2 }
            { "zip" : 57088 } -->> { "zip" : "57500" } on : shard0002 { "t" : 4, "i" : 3 }
            { "zip" : 57500 } -->> { "zip" : "58140" } on : shard0001 { "t" : 4, "i" : 0 }
            { "zip" : 58140 } -->> { "zip" : "59000" } on : shard0000 { "t" : 4, "i" : 1 }
            { "zip" : 59000 } -->> { "zip" : { "$maxKey" : 1 } } on : shard0000 { "t" : 3, "i" : 3 }
    {  "_id" : "test",  "partitioned" : false,  "primary" : "shard0000" }

← Upgrade Config Servers to Replica Set (Downtime) Migrate a Sharded Cluster to Different Hardware →