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View Cluster Configuration

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  • List Databases with Sharding Enabled
  • List Shards
  • View Cluster Details

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 mongosh to a mongos instance 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 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" }

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