db.collection.remove()

Write Concern写入关注

The remove() method uses the delete command, which uses the default write concern. remove()方法使用delete命令，该命令使用默认的写入关注。To specify a different write concern, include the write concern in the options parameter.要指定不同的写入关注，请在options参数中包含该写入关注。

Query Considerations查询注意事项

By default, remove() removes all documents that match the query expression. 默认情况下，remove()会删除所有与查询表达式匹配的文档。Specify the justOne option to limit the operation to removing a single document. 指定justOne选项将操作限制为删除单个文档。To delete a single document sorted by a specified order, use the findAndModify() method.要删除按指定顺序排序的单个文档，请使用findAndModify()方法。

When removing multiple documents, the remove operation may interleave with other read and/or write operations to the collection.当删除多个文档时，删除操作可能会与对集合的其他读取和/或写入操作交错进行。

Time Series Collections时间序列集合

You cannot use the remove() method on a time series collection.不能对时间序列集合使用remove()方法。

Sharded Collections分片集合

All remove() operations for a sharded collection that specify the justOne: true option must include the shard key or the _id field in the query specification.指定justOne:true选项的分片集合的所有remove()操作都必须在查询规范中包括分片键或_id字段。

remove() operations specifying justOne: true in a sharded collection which do not contain either the shard key or the _id field return an error.在不包含分片键或_id字段的分片集合中指定justOne:true的remove()操作返回错误。

Transactions事务

db.collection.remove() can be used inside multi-document transactions.可以在多文档事务中使用。

Do not explicitly set the write concern for the operation if run in a transaction. 如果在事务中运行，请不要显式设置操作的写入关注。To use write concern with transactions, see Transactions and Write Concern.要在事务中使用写入关注，请参阅事务和写入关注。

Remove All Documents from a Collection从集合中删除所有文档

To remove all documents in a collection, call the remove method with an empty query document {}. 若要删除集合中的所有文档，请使用空查询文档{}调用remove方法。The following operation deletes all documents from the bios collection:以下操作将删除bios集合中的所有文档：

db.bios.remove( { } )

This operation is not equivalent to the drop() method.此操作不等同于drop()方法。

To remove all documents from a collection, it may be more efficient to use the drop() method to drop the entire collection, including the indexes, and then recreate the collection and rebuild the indexes.要从集合中删除所有文档，使用drop()方法删除整个集合（包括索引），然后重新创建集合并重新生成索引可能会更有效。

Remove All Documents that Match a Condition删除所有符合条件的文档

To remove the documents that match a deletion criteria, call the remove() method with the <query> parameter:要删除符合删除条件的文档，请使用<query>参数调用remove()方法：

The following operation removes all the documents from the collection products where qty is greater than 20:以下操作将从集合products中删除qty大于20的所有文档：

db.products.remove( { qty: { $gt: 20 } } )

Override Default Write Concern覆盖默认写入关注

The following operation to a replica set removes all the documents from the collection products where qty is greater than 20 and specifies a write concern of w: 2 with a wtimeout of 5000 milliseconds. 以下对副本集的操作将从集合products中删除qty大于20的所有文档，并指定写入关注为w:2、wtimeout为5000毫秒。This operation either returns after the write propagates to both the primary and one secondary, or times out after 5 seconds.此操作要么在写入传播到主和一个辅助后返回，要么在5秒后超时。

db.products.remove(
    { qty: { $gt: 20 } },
    { writeConcern: { w: "majority", wtimeout: 5000 } }
)

Remove a Single Document that Matches a Condition删除符合条件的单个文档

To remove the first document that match a deletion criteria, call the remove method with the query criteria and the justOne parameter set to true or 1.要删除与删除条件匹配的第一个文档，请调用remove方法，同时将query条件和justOne参数设置为true或1。

The following operation removes the first document from the collection products where qty is greater than 20:以下操作将从集合products中删除qty大于20的第一个文档：

db.products.remove( { qty: { $gt: 20 } }, true )

Specify Collation指定排序规则

collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.允许用户为字符串比较指定特定于语言的规则，例如字母大小写和重音标记的规则。

A collection myColl has the following documents:集合myColl包含以下文档：

{ _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:以下操作包括collation选项：

db.myColl.remove(
   { category: "cafe", status: "A" },
   { collation: { locale: "fr", strength: 1 } }
)

Use Variables in let在let中使用变量

To define variables that you can access elsewhere in the command, use the let option.要定义可以在命令的其他地方访问的变量，请使用let选项。

Create a collection cakeFlavors:创建一个集合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:以下示例在let中定义了targetFlavor变量，并使用该变量删除草莓蛋糕风味：

db.cakeFlavors.remove(
   { $expr: { $eq: [ "$flavor", "$$targetFlavor" ] } },
   { let : { targetFlavor: "strawberry" } }
)

Successful Results成功的结果

The remove() returns a WriteResult() object that contains the status of the operation. remove()返回一个WriteResult()对象，该对象包含操作的状态。Upon success, the WriteResult() object contains information on the number of documents removed:成功后，WriteResult()对象包含有关删除的文档数的信息：

WriteResult({ "nRemoved" : 4 })

Write Concern Errors写入关注错误

If the remove() method encounters write concern errors, the results include the WriteResult.writeConcernError field:如果remove()方法遇到写入关注错误，结果包括WriteResult.writeConcernError字段：

WriteResult({
  "nRemoved" : 7,
  "writeConcernError" : {
    "code" : 64,
    "codeName" : "WriteConcernFailed",
    "errmsg" : "waiting for replication timed out",
    "errInfo" : {
      "wtimeout" : true,
      "writeConcern" : {    // Added in MongoDB 4.4
        "w" : "majority",
        "wtimeout" : 1,
        "provenance" : "getLastErrorDefaults"
      }
    }
  }
})

Errors Unrelated to Write Concern与写入关注无关的错误

If the remove() method encounters a non-write concern error, the results include WriteResult.writeError field:如果remove()方法遇到非写入关注错误，结果包括WriteResult.writeError字段：

WriteResult({
   "nRemoved" : 0,
   "writeError" : {
      "code" : 2,
      "errmsg" : "unknown top level operator: $invalidFieldName"
   }
})