delete

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Definition

Syntax
Command Fields
Behavior
Examples
Output

Definition

delete

The delete command removes documents from a collection. A single delete command can contain multiple delete specifications. The delete methods provided by the MongoDB drivers use this command internally.

Changed in version 5.0.

Tip

In mongosh, this command can also be run through the deleteOne(), deleteMany(), and findOneAndDelete() helper methods.

Helper methods are convenient for mongosh users, but they may not return the same level of information as database commands. In cases where the convenience is not needed or the additional return fields are required, use the database command.

Returns:	A document that contains the status of the operation. See Output for details.

Syntax

The command has the following syntax:

 db.runCommand(
    {
      delete: <collection>,
      deletes: [
         {
           q : <query>,
           limit : <integer>,
           collation: <document>,
           hint: <document|string>
         },
         ...
      ],
      comment: <any>,
      let: <document>, // Added in MongoDB 5.0
      ordered: <boolean>,
      writeConcern: { <write concern> },
      maxTimeMS: <integer>
   }
)

Command Fields

The command takes the following fields:

Field

Type

Description

delete

string

The name of the target collection.

deletes

array

An array of one or more delete statements to perform in the named collection.

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.

let

document

Optional.

Specifies a document with a list of variables. This allows you to improve command readability by separating the variables from the query text.

The document syntax is:

{ <variable_name_1>: <expression_1>,
  ...,
  <variable_name_n>: <expression_n> }

The variable is set to the value returned by the expression, and cannot be changed afterwards.

To access the value of a variable in the command, use the double dollar sign prefix ($$) together with your variable name in the form $$<variable_name>. For example: $$targetTotal.

Note

To use a variable to filter results, you must access the variable within the $expr operator.

For a complete example using let and variables, see Use Variables in let.

New in version 5.0.

ordered

boolean

Optional. If true, then when a delete statement fails, return without performing the remaining delete statements. If false, then when a delete statement fails, continue with the remaining delete statements, if any. Defaults to true.

writeConcern

document

Optional. A document expressing the write concern of the delete command. Omit to use the default write concern.

Do not explicitly set the write concern for the operation if run in a transaction. To use write concern with transactions, see Transactions and Write Concern.

maxTimeMS

non-negative integer

Optional.

Specifies a time limit in milliseconds. If you do not specify a value for maxTimeMS, operations will not time out. A value of 0 explicitly specifies the default unbounded behavior.

MongoDB terminates operations that exceed their allotted time limit using the same mechanism as db.killOp(). MongoDB only terminates an operation at one of its designated interrupt points.

Each element of the deletes array contains the following fields:

Field

Type

Description

document

The query that matches documents to delete.

limit

integer

The number of matching documents to delete. Specify either a 0 to delete all matching documents or 1 to delete a single document.

collation

document

Optional.

Specifies the collation to use for the operation.

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

The collation option has the following syntax:

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

When specifying collation, the locale field is mandatory; all other collation fields are optional. For descriptions of the fields, see Collation Document.

If the collation is unspecified but the collection has a default collation (see db.createCollection()), the operation uses the collation specified for the collection.

If no collation is specified for the collection or for the operations, MongoDB uses the simple binary comparison used in prior versions for string comparisons.

You cannot specify multiple collations for an operation. For example, you cannot specify different collations per field, or if performing a find with a sort, you cannot use one collation for the find and another for the sort.

hint

Document or string

Optional. A document or string that specifies the index to use to support the query predicate.

The option can take an index specification document or the index name string.

If you specify an index that does not exist, the operation errors.

For an example, see Specify hint for Delete Operations.

New in version 4.4.

Behavior

Sharded Collections

All delete operations for a sharded collection that specify the limit: 1 option must include the shard key or the _id field in the query specification.

delete operations specifying limit: 1 in a sharded collection which do not contain either the shard key or the _id field return an error.

Limits

The total size of all the queries (i.e. the q field values) in the deletes array must be less than or equal to the maximum BSON document size.

The total number of delete documents in the deletes array must be less than or equal to the maximum bulk size.

Transactions

delete can be used inside multi-document transactions.

Do not explicitly set the write concern for the operation if run in a transaction. To use write concern with transactions, see Transactions and Write Concern.

Important

In most cases, multi-document transaction incurs a greater performance cost over single document writes, and the availability of multi-document transactions should not be a replacement for effective schema design. For many scenarios, the denormalized data model (embedded documents and arrays) will continue to be optimal for your data and use cases. That is, for many scenarios, modeling your data appropriately will minimize the need for multi-document transactions.

For additional transactions usage considerations (such as runtime limit and oplog size limit), see also Production Considerations.

Examples

Limit the Number of Documents Deleted

The following example deletes from the orders collection one document that has the status equal to D by specifying the limit of 1:

db.runCommand(
   {
      delete: "orders",
      deletes: [ { q: { status: "D" }, limit: 1 } ]
   }
)

The returned document shows that the command deleted 1 document. See Output for details.

{ "ok" : 1, "n" : 1 }

Note

All delete operations for a sharded collection that specify the limit: 1 option must include the shard key or the _id field in the query specification.

delete operations specifying limit: 1 in a sharded collection which do not contain either the shard key or the _id field return an error.

Delete All Documents That Match a Condition

The following example deletes from the orders collection all documents that have the status equal to D by specifying the limit of 0:

db.runCommand(
   {
      delete: "orders",
      deletes: [ { q: { status: "D" }, limit: 0 } ],
      writeConcern: { w: "majority", wtimeout: 5000 }
   }
)

The returned document shows that the command found and deleted 13 documents. See Output for details.

{ "ok" : 1, "n" : 13 }

Delete All Documents from a Collection

Delete all documents in the orders collection by specifying an empty query condition and a limit of 0:

db.runCommand(
   {
      delete: "orders",
      deletes: [ { q: { }, limit: 0 } ],
      writeConcern: { w: "majority", wtimeout: 5000 }
   }
)

The returned document shows that the command found and deleted 35 documents in total. See Output for details.

{ "ok" : 1, "n" : 35 }

Bulk Delete

The following example performs multiple delete operations on the orders collection:

db.runCommand(
   {
      delete: "orders",
      deletes: [
         { q: { status: "D" }, limit: 0 },
         { q: { cust_num: 99999, item: "abc123", status: "A" }, limit: 1 }
      ],
      ordered: false,
      writeConcern: { w: 1 }
   }
)

The returned document shows that the command found and deleted 21 documents in total for the two delete statements. See Output for details.

{ "ok" : 1, "n" : 21 }

Specify Collation

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

A collection myColl has the following documents:

{ _id: 1, category: "café", status: "A" }
{ _id: 2, category: "cafe", status: "a" }
{ _id: 3, category: "cafE", status: "a" }

The following operation includes the collation option:

db.runCommand({
   delete: "myColl",
   deletes: [
     { q: { category: "cafe", status: "a" }, limit: 0, collation: { locale: "fr", strength: 1 } }
   ]
})

Specify `hint` for Delete Operations

New in version 4.4.

In mongosh, create a members collection with the following documents:

db.members.insertMany([
   { "_id" : 1, "member" : "abc123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 2, "member" : "xyz123", "status" : "A", "points" : 60,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" },
   { "_id" : 3, "member" : "lmn123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 4, "member" : "pqr123", "status" : "D", "points" : 20,  "misc1" : "Deactivated", "misc2" : null },
   { "_id" : 5, "member" : "ijk123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 6, "member" : "cde123", "status" : "A", "points" : 86,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" }
])

Create the following indexes on the collection:

db.members.createIndex( { status: 1 } )
db.members.createIndex( { points: 1 } )

The following delete operation explicitly hints to use the index { status: 1 }:

db.runCommand({
   delete: "members",
   deletes: [
     { q: { "points": { $lte: 20 }, "status": "P" }, limit: 0, hint: { status: 1 } }
   ]
})

Note

If you specify an index that does not exist, the operation errors.

To see the index used, run explain on the operation:

db.runCommand(
   {
     explain: {
       delete: "members",
       deletes: [
         { q: { "points": { $lte: 20 }, "status": "P" }, limit: 0, hint: { status: 1 } }
       ]
     },
     verbosity: "queryPlanner"
   }
)

Use Variables in `let`

New in version 5.0.

To define variables that you can access elsewhere in the command, use the let option.

Note

To filter results using a variable, you must access the variable within the $expr operator.

Create a collection cakeFlavors:

db.cakeFlavors.insertMany( [
   { _id: 1, flavor: "chocolate" },
   { _id: 2, flavor: "strawberry" },
   { _id: 3, flavor: "cherry" }
] )

The following example defines a targetFlavor variable in let and uses the variable to delete the strawberry cake flavor:

db.runCommand( {
   delete: db.cakeFlavors.getName(),
   deletes: [ {
      q: { $expr: { $eq: [ "$flavor", "$$targetFlavor" ] } },
      limit: 1
   } ],
   let : { targetFlavor: "strawberry" }
} )

Output

The returned document contains a subset of the following fields:

delete.ok: The status of the command.

delete.n: The number of documents deleted.

delete.writeErrors

An array of documents that contains information regarding any error encountered during the delete operation. The writeErrors array contains an error document for each delete statement that errors.

Each error document contains the following information:

delete.writeErrors.index: An integer that identifies the delete statement in the deletes array, which uses a zero-based index.

delete.writeErrors.code: An integer value identifying the error.

delete.writeErrors.errmsg: A description of the error.

delete.writeConcernError

Document that describe error related to write concern and contains the fields:

delete.writeConcernError.code: An integer value identifying the cause of the write concern error.

delete.writeConcernError.errmsg: A description of the cause of the write concern error.

delete.writeConcernError.errInfo.writeConcern

New in version 4.4.

The write concern object used for the corresponding operation. For information on write concern object fields, see Write Concern Specification.

The write concern object may also contain the following field, indicating the source of the write concern:

delete.writeConcernError.errInfo.writeConcern.provenance

A string value indicating where the write concern originated (known as write concern provenance). The following table shows the possible values for this field and their significance:

Provenance	Description
`clientSupplied`	The write concern was specified in the application.
`customDefault`	The write concern originated from a custom defined default value. See `setDefaultRWConcern`.
`getLastErrorDefaults`	The write concern originated from the replica set's `settings.getLastErrorDefaults` field.
`implicitDefault`	The write concern originated from the server in absence of all other write concern specifications.

The following is an example document returned for a successful delete command:

{ ok: 1, n: 1 }

The following is an example document returned for a delete command that encountered an error because it specified a non-existent index in the hint field:

{
  n: 0,
  writeErrors: [
    {
      index: 0,
      code: 2,
      errmsg: 'error processing query: ns=test.products: hat $eq "bowler"\n' +
        'Sort: {}\n' +
        'Proj: {}\n' +
        ' planner returned error :: caused by :: hint provided does not correspond to an existing index'
    }
  ],
  ok: 1
}

Back

Query and Write Operation Commands

find

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Definition

Tip

Syntax

Command Fields

Note

Behavior

Sharded Collections

Limits

Transactions

Important

Examples

Limit the Number of Documents Deleted

Note

Delete All Documents That Match a Condition

Delete All Documents from a Collection

Bulk Delete

Specify Collation

Specify hint for Delete Operations

Note

Use Variables in let

Note

Output

delete

Specify `hint` for Delete Operations

Use Variables in `let`