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listCollections

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  • Definition
  • Behavior
  • Required Access
  • Output
  • Example
  • Learn More

Definition

listCollections

Retrieves information, including the names and creation options, for the collections and views in a database.

The listCollections command returns a document that contains information you can use to create a cursor on the collection.

mongo provides the db.getCollectionInfos() and the db.getCollectionNames() helper methods.

The command has the following form:

{ listCollections: 1, filter: <document>, nameOnly: <boolean>, authorizedCollections: <boolean>, comment: <any> }

The command can take the following optional fields:

Field
Type
Description
filter
document

Optional. A query expression to filter the list of collections.

You can specify a query expression on any of the fields returned by listCollections.

nameOnly
boolean

Optional. A flag to indicate whether the command should return just the collection/view names and type or return both the name and other information.

Returning just the name and type (view or collection) does not take collection-level locks whereas returning full collection information locks each collection in the database.

The default value is false.

Note

When nameOnly is true, your filter expression can only filter based on a collection's name and type. No other fields are available.

authorizedCollections
boolean

Optional. A flag, when set to true and used with nameOnly: true, that allows a user without the required privilege (i.e. listCollections action on the database) to run the command when access control is enforced.

When both authorizedCollections and nameOnly options are set to true, the command returns only those collections for which the user has privileges. For example, if a user has find action on specific collections, the command returns only those collections; or, if a user has find or any other action, on the database resource, the command lists all collections in the database.

The default value is false. That is, the user must have listCollections action on the database to run the command.

For a user who has listCollections action on the database, this option has no effect since the user has privileges to list the collections in the database.

When used without nameOnly: true, this option has no effect. That is, the user must have the required privileges to run the command when access control is enforced. Otherwise, the user is unauthorized to run the command.

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).

New in version 4.4.

Behavior

Filter

Use a filter to limit the results of listCollections. You can specify a filter on any of the fields returned in the listCollections result set.

Locks

listCollections takes an intent shared lock lock on each collection in the database when listCollections holds an intent shared lock on the database.

To learn about locks, see What type of locking does MongoDB use?.

Client Disconnection

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

Replica Set Member State Restriction

Starting in MongoDB 4.4, to run on a replica set member, listCollections operations require the member to be in PRIMARY or SECONDARY state. If the member is in another state, such as STARTUP2, the operation errors.

In previous versions, the operations also run when the member is in STARTUP2. The operations wait until the member transitioned to RECOVERING.

Required Access

The listCollections command requires the listCollections action when access control is enforced. Users must have privileges that grant the listCollections action on the database to run listCollections.

For example, the following command grants the privilege to run db.getCollectionInfos() against the test database:

{ resource: { db: "test", collection: "" }, actions: [ "listCollections" ] }

The built-in role read provides the privilege to run listCollections for a specific database.

Users without the required read privilege can run listCollections when authorizedCollections and nameOnly are both set to true. In this case, the command returns the names and types for collection(s) where the user has privileges.

For example, consider a user with a role that grants the following find privilege:

{ resource: { db: "sales", collection: "currentQuarter" }, actions: [ "find" ] }

The user can run listCollections if authorizedCollections and nameOnly are both set to true.

db.runCommand(
   {
       listCollections: 1.0,
       authorizedCollections: true,
       nameOnly: true
   }
)

The operation returns the name and type of the currentQuarter collection.

However, the following operations return an error if the user does not have the required access authorization:

db.runCommand(
   {
       listCollections: 1.0,
       authorizedCollections: true
   }
)
db.runCommand(
   {
       listCollections: 1.0,
       nameOnly: true
   }
)

show collections

The mongosh method show collections is similar to:

db.runCommand(
   {
       listCollections: 1.0,
       authorizedCollections: true,
       nameOnly: true
   }
)

  • For users with the required access, show collections lists the non-system collections for the database.

  • For users without the required access, show collections lists only the collections for which the users has privileges.

Output

listCollections.cursor

A document that contains information with which to create a cursor to documents that contain collection names and options. The cursor information includes the cursor id, the full namespace for the command, as well as the first batch of results. Each document in the batch output contains the following fields:

Field
Type
Description
name
String
Name of the collection.
type
String
Type of data store. Returns collection for collections and view for views.
options
Document

Collection options.

These options correspond directly to the options available in db.createCollection(). For the descriptions on the options, see db.createCollection().

info
Document

Lists the following fields related to the collection:

readOnly
boolean. If true the data store is read only.
uuid

UUID. Once established, the collection UUID does not change. The collection UUID remains the same across replica set members and shards in a sharded cluster.

New in version 3.6.

idIndex
Document
Provides information on the _id index for the collection.
listCollections.ok

The return value for the command. A value of 1 indicates success.

Example

List All Collections

The music database contains three collections, motorhead, taylorSwift, and ramones.

To list the collections in the database, you can use the built-in mongo command, show collections.

show collections

The output is:

motorhead
ramones
taylorSwift

To get a similar list with the listCollections collections command, use the nameOnly option.

db.runCommand(
   {
      listCollections: 1.0,
      nameOnly: true
   }
)

The output is:

{
 "cursor" :
    {
        "id" : NumberLong(0),
        "ns" : "records.$cmd.listCollections",
        "firstBatch" :
           [
               {
                   "name" : "motorhead",
                   "type" : "collection"
               },
               {
                   "name" : "taylorSwift",
                   "type" : "collection"
               },
               {
                   "name" : "ramones",
                   "type" : "collection"
               }
           ]
    },
 "ok" : 1
}

To get more detailed information, remove the nameOnly option.

db.runCommand(
   {
      listCollections: 1.0
   }
)

The output is:

{
    "cursor" :
       {
           "id" : NumberLong(0),
           "ns" : "records.$cmd.listCollections",
           "firstBatch" :
              [
                  {
                      "name" : "motorhead",
                      "type" : "collection",
                      "options" : {},
                      "info" :
                         {
                            "readOnly" : false,
                            "uuid" : UUID("09ef1858-2831-47d2-a3a7-9a29a9cfeb94")
                         },
                      "idIndex" :
                         {
                            "v" : 2,
                            "key" : { "_id" : 1 },
                            "name" : "_id_"
                         }
                  },
                  {
                      "name" : "taylorSwift",
                      "type" : "collection",
                      "options" : {},
                      "info" :
                          {
                             "readOnly" : false,
                             "uuid" : UUID("6c46c8b9-4999-4213-bcef-9a36b0cff228")
                          },
                      "idIndex" :
                         {
                             "v" : 2,
                             "key" : { "_id" : 1 },
                             "name" : "_id_"
                         }
                  },
                  {
                      "name" : "ramones",
                      "type" : "collection",
                      "options" : {},
                      "info" :
                         {
                             "readOnly" : false,
                             "uuid" : UUID("7e1925ba-f2f9-4e42-90e4-8cafd434a6c4")
                         },
                      "idIndex" :
                         {
                             "v" : 2,
                             "key" : { "_id" : 1 },
                             "name" : "_id_"
                         }
                  }
               ]
       },
    "ok" : 1
}

Learn More

For collection options:

For collection information:

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