db.collection.deleteOne()

Deletion Order删除顺序

db.collection.deleteOne() deletes the first document that matches the filter. 删除与筛选器匹配的第一个文档。Use a field that is part of a unique index such as _id for precise deletions.请使用作为唯一索引一部分的字段，例如_id，以进行精确删除。

Capped Collections封顶集合

db.collection.deleteOne() returns a WriteError exception if used on a capped collection.如果在封顶集合上使用db.collection.deleteOne()，则返回WriteError异常。

Time Series Collections时间序列集合

db.collection.deleteOne() returns a WriteError exception if used on a time series collection.如果在时间序列集合上使用，则db.collection.deleteOne()返回WriteError异常。

Sharded Collections分片集合

db.collection.deleteOne() operations on a sharded collection must include the shard key or the _id field in the query specification. 对分片集合的操作必须包括查询规范中的分片键或_id字段。db.collection.deleteOne() operations in a sharded collection which do not contain either the shard key or the _id field return an error.分片集合中不包含分片键或_id字段的db.collection.deleteOne()操作将返回错误。

Transactions事务

db.collection.deleteOne() 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点。To use write concern with transactions, see Transactions and Write Concern.要对事务使用写关注点，请参阅事务和写关注点。

Delete a Single Document删除单个文档

The orders collection has documents with the following structure:orders集合具有以下结构的文档：

{
   _id: ObjectId("563237a41a4d68582c2509da"),
   stock: "Brent Crude Futures",
   qty: 250,
   type: "buy-limit",
   limit: 48.90,
   creationts: ISODate("2015-11-01T12:30:15Z"),
   expiryts: ISODate("2015-11-01T12:35:15Z"),
   client: "Crude Traders Inc."
}

The following operation deletes the order with _id: ObjectId("563237a41a4d68582c2509da") :以下操作删除带有_id: ObjectId("563237a41a4d68582c2509da")的订单：

try {
   db.orders.deleteOne( { "_id" : ObjectId("563237a41a4d68582c2509da") } );
} catch (e) {
   print(e);
}

The operation returns:操作返回：

{ "acknowledged" : true, "deletedCount" : 1 }

The following operation deletes the first document with expiryts greater than ISODate("2015-11-01T12:40:15Z")以下操作删除expiryts大于ISODate("2015-11-01T12:40:15Z")的第一个文档

try {
   db.orders.deleteOne( { "expiryts" : { $lt: ISODate("2015-11-01T12:40:15Z") } } );
} catch (e) {
   print(e);
}

The operation returns:操作返回：

{ "acknowledged" : true, "deletedCount" : 1 }

deleteOne() with Write Concern带写入关注

Given a three member replica set, the following operation specifies a w of majority, wtimeout of 100:给定一个三成员副本集，以下操作指定w为"majority"，wtimeout为100：

try {
   db.orders.deleteOne(
       { "_id" : ObjectId("563237a41a4d68582c2509da") },
       { w : "majority", wtimeout : 100 }
   );
} catch (e) {
   print (e);
}

If the acknowledgement takes longer than the wtimeout limit, the following exception is thrown:如果确认花费的时间超过wtimeout限制，将引发以下异常：

WriteConcernError({
   "code" : 64,
   "errmsg" : "waiting for replication timed out",
   "errInfo" : {
     "wtimeout" : true,
     "writeConcern" : {
    // Added in MongoDB 4.4
       "w" : "majority",
       "wtimeout" : 100,
       "provenance" : "getLastErrorDefaults"
     }
   }
})

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.排序规则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:以下操作包括排序规则选项：

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

Specify hint for Delete Operations指定删除操作的hint

In mongosh, create a members collection with the following documents:在mongosh中，使用以下文档创建members集合：

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:在集合上创建以下索引：

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

The following delete operation explicitly hints to use the index { status: 1 }:以下删除操作明确提示使用索引{ status: 1 }：

db.members.deleteOne(
   { "points": { $lte: 20 }, "status": "P" },
   { hint: { status: 1 } }
)

The delete command returns the following:delete命令返回以下内容：

{ "acknowledged" : true, "deletedCount" : 1 }

To view the indexes used, you can use the $indexStats pipeline:要查看使用的索引，可以使用$indexStats管道：

db.members.aggregate( [ { $indexStats: { } }, { $sort: { name: 1 } } ] )

The accesses.ops field in the $indexStats output indicates the number of operations that used the index.$indexStats输出中的accesses.ops字段指示使用索引的操作数。