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listDatabases

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  • Definition
  • Syntax
  • Command Fields
  • Behavior
  • Examples
  • Output

Definition

listDatabases

The listDatabases command provides a list of all existing databases along with basic statistics about them. The listDatabases must run against the admin database, as in the following example:

Syntax

db.adminCommand(
   {
     listDatabases: 1
   }
)

The value (e.g. 1) does not affect the output of the command.

Command Fields

The command can take the following optional fields:

Field
Type
Description
filter
document

Optional. A query predicate that determines which databases are listed.

You can specify a condition on any of the fields in the output of listDatabases:

  • name

  • sizeOnDisk

  • empty

  • shards

nameOnly
boolean

Optional. A flag to indicate whether the command should return just the database names, or return both database names and size information.

Returning size information requires locking each database one at a time, while returning only names does not require locking any database.

The default value is false, so listDatabases returns the name and size information of each database.

authorizedDatabases
boolean

Optional. A flag that determines which databases are returned based on the user privileges when access control is enabled.

  • If authorizedDatabases is unspecified, and

    • If the user has listDatabases action on the cluster resource, listDatabases command returns all databases.

    • If the user does not have listDatabases action on the cluster:

      • For MongoDB 4.0.6+, listDatabases command returns only the databases for which the user has privileges (including databases for which the user has privileges on specific collections).

      • For MongoDB 4.0.5, listDatabases command returns only the databases for which the user has the find action on the database resource (and not the collection resource).

  • If authorizedDatabases is true,

    • For MongoDB 4.0.6+, listDatabases command returns only the databases for which the user has privileges (including databases for which the user has privileges on specific collections).

    • For MongoDB 4.0.5, listDatabases command returns only the databases for which the user has the find action on the database resource (and not the collection resource).

  • If authorizedDatabases is false, and

For more information, see Behavior.

comment
any

Optional. A user-provided comment to attach to this command. Once set, this comment appears alongside records of this command in the following locations:

A comment can be any valid BSON type (string, integer, object, array, etc).

Behavior

When authentication is enabled, the listDatabases command returns different values based on the privileges assigned to the user who executes the command and the authorizedDatabases command option:

  • If authorizedDatabases is unspecified, and

    • If the user has listDatabases action on the cluster resource, listDatabases command returns all databases.

    • If the user does not have listDatabases action on the cluster, listDatabases command returns only the databases for which the user has privileges (including databases for which the user has privileges on specific collections).

  • If authorizedDatabases is true, listDatabases command returns only the databases for which the user has privileges (including databases for which the user has privileges on specific collections).

  • If authorizedDatabases is false, and

Client Disconnection

Starting in MongoDB 4.2, if the client that issued listDatabases disconnects before the operation completes, MongoDB marks listDatabases for termination using killOp.

Replica Set Member State Restriction

To run on a replica set member, listDatabases operations require the member to be in PRIMARY or SECONDARY state. If the member is in another state, such as STARTUP2, the operation errors.

Examples

List Database Names and Sizes

Run listDatabases against the admin database:

db.adminCommand( { listDatabases: 1 } )

The following is an example of a listDatabases result:

{
   "databases" : [
      {
         "name" : "admin",
         "sizeOnDisk" : 83886080,
         "empty" : false
      },
      {
         "name" : "local",
         "sizeOnDisk" : 83886080,
         "empty" : false
      },
      {
         "name" : "test",
         "sizeOnDisk" : 83886080,
         "empty" : false
      }
   ],
   "totalSize" : 251658240,
   "totalSizeMb" : 251,
   "ok" : 1
}

List Database Names Only

Run listDatabases against the admin database. Specify the nameOnly: true option:

db.adminCommand( { listDatabases: 1, nameOnly: true} )

The following is an example of a listDatabases results when run with the nameOnly: true option:

{
   "databases" : [
      {
         "name" : "admin"
      },
      {
         "name" : "local"
      },
      {
         "name" : "test"
      }
   ],
   "ok" : 1
}

List Databases That Match the Filter

Run listDatabases against the admin database. Specify the filter option to only list databases that match the specified filter criteria.

For example, the following specifies a filter such that listDatabases only returns information on databases whose name matches the specified regular expression:

db.adminCommand( { listDatabases: 1, filter: { "name": /^rep/ } } )

Sharded Clusters

When executed against a mongos instance, listDatabases:

  • adds a shards embedded document to each database's summary document if nameOnly: false, and

  • excludes the local database.

Each element in the shards embedded document consists of a field whose key gives the name of a collection on that shard, and whose value represents the collection's size in bytes.

The sizeOnDisk field represents the total size of all listed collections and indexes.

For example:

{
  "databases" : [
    {
      "name" : "admin",
      "sizeOnDisk" : 16384,
      "empty" : false,
      "shards" : {
        "config" : 16384
      }
    },
    {
      "name" : "config",
      "sizeOnDisk" : 176128,
      "empty" : false,
      "shards" : {
        "clients" : 28672,
        "patients" : 8192,
        "config" : 139264
      }
    },
    {
      "name" : "test",
      "sizeOnDisk" : 12288,
      "empty" : false,
      "shards" : {
        "clients" : 12288
      }
    }
  ],
  "totalSize" : 204800,
  "totalSizeMb" : 0,
  "ok" : 1
}

Tip

See also:

Use Database Commands.

Output

listDatabases.databases

Type: Array

Array of documents, each containing information on a single database.

listDatabases.databases.name

Type: String

Name of the database.

listDatabases.databases.sizeOnDisk

Type: Integer

Total size of the database files on disk, expressed in bytes.

listDatabases.databases.empty

Type: Boolean

Specifies whether the database is empty.

listDatabases.databases.shards

Type: Document

Each element in the shards document consists of a field whose key gives the name of a collection on that shard, and whose value represents the collection's size in bytes.

shards only appears in the output if nameOnly: false.

See Sharded Clusters for details.

listDatabases.totalSize

Type: Integer

Sum of all the sizeOnDisk fields in bytes.

listDatabases.totalSizeMb

Type: Integer

Sum of all the sizeOnDisk fields, expressed in megabytes.

listDatabases.ok

Type: Integer

Return value for the command. A value of 1 indicates success.

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