killCursors

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Definition
Syntax
Command Fields
Required Access
killCursors and Transactions
Example

Definition

killCursors

Kills the specified cursor or cursors for a collection. MongoDB drivers use the killCursors command as part of the client-side cursor implementation.

Note

In general, applications should not use the killCursors command directly.

The killCursors command must be run against the database of the collection whose cursors you wish to kill.

To run killCursors, use the db.runCommand( { <command> } ) method.

Syntax

The command has the following syntax:

db.runCommand(
   {
     killCursors: <collection>,
     cursors: [ <cursor id1>, ... ], comment: <any>
   }
)

Command Fields

The command takes the following fields:

Field	Type	Description
`killCursors`	string	The name of the collection.
`cursors`	array	The ids of the cursors to kill.
`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: mongod log messages, in the `attr.command.cursor.comment` field. Database profiler output, in the `command.comment` field. `currentOp` output, in the `command.comment` field. A comment can be any valid BSON type (string, integer, object, array, etc). New in version 4.4.

Required Access

Kill Own Cursors

In MongoDB 4.2 and later, users can always kill their own cursors, regardless of whether the users have the privilege to killCursors. Cursors are associated with the users at the time of cursor creation.
In MongoDB 3.6.3 through MongoDB 4.0.x, users require killCursors privilege to kill their own cursors. Cursors are associated with the users at the time of cursor creation.

Kill Any Cursor

If a user possesses the killAnyCursor privilege, that user may kill any cursor, even cursors created by other users.

`killCursors` and Transactions

Starting in MongoDB 4.2, you cannot specify killCursors as the first operation in a transaction.

Example

Consider the following find operation on the test.restaurants collection:

use test
db.runCommand(
   { find: "restaurants",
     filter: { stars: 5 },
     projection: { name: 1, rating: 1, address: 1 },
     sort: { name: 1 },
     batchSize: 5
   }
)

which returns the following:

{
   "waitedMS" : NumberLong(0),
   "cursor" : {
      "firstBatch" : [
         {
            "_id" : ObjectId("57506d63f578028074723dfd"),
            "name" : "Cakes and more"
         },
         {
            "_id" : ObjectId("57506d63f578028074723e0b"),
            "name" : "Pies and things"
         },
         {
            "_id" : ObjectId("57506d63f578028074723e1d"),
            "name" : "Ice Cream Parlour"
         },
         {
            "_id" : ObjectId("57506d63f578028074723e65"),
            "name" : "Cream Puffs"
         },
         {
            "_id" : ObjectId("57506d63f578028074723e66"),
            "name" : "Cakes and Rolls"
         }
      ],
      "id" : NumberLong("18314637080"),
      "ns" : "test.restaurants"
   },
   "ok" : 1
}

To kill this cursor, use the killCursors command.

use test

db.runCommand( { killCursors: "restaurants", cursors: [ NumberLong("18314637080") ] } )

killCursors returns the following operation details:

{
   "cursorsKilled" : [
      NumberLong("18314637080")
   ],
   "cursorsNotFound" : [ ],
   "cursorsAlive" : [ ],
   "cursorsUnknown" : [ ],
   "ok" : 1
}

← getParameterkillOp →