db.collection.deleteMany()

Time Series Collections时间序列集合

db.collection.deleteMany() throws a WriteError exception if used on a time series collection. 如果在时间序列集合上使用db.collection.deleteMany()，则会引发WriteError异常。To remove all documents from a time series collection, use db.collection.drop().要从时间序列集合中删除所有文档，请使用db.collection.drop()。

Delete a Single Document删除单个文档

To delete a single document, use db.collection.deleteOne() instead.若要删除单个文档，请改用db.collection.deleteOne()。

Alternatively, use a field that is a part of a unique index such as _id.或者，使用作为唯一索引（如_id）一部分的字段。

Transactions事务

db.collection.deleteMany() 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。

Primary Node Failure主节点故障

db.collection.deleteMany() deletes documents one at a time. 一次删除一个文档。If the primary node fails during a db.collection.deleteMany() operation, documents that were not yet deleted from secondary nodes are not deleted from the collection.如果主节点在db.collection.deleteMany()操作期间失败，则尚未从辅助节点删除的文档不会从集合中删除。

Delete Multiple Documents删除多个文档

The orders collection has documents with the following structure:orders集合包含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 all documents where client : "Crude Traders Inc.":以下操作删除客户为client : "Crude Traders Inc."的所有文档：

try {
   db.orders.deleteMany( { "client" : "Crude Traders Inc." } );
} catch (e) {
   print (e);
}

The operation returns:操作返回：

{ "acknowledged" : true, "deletedCount" : 10 }

The following operation deletes all documents where stock : "Brent Crude Futures" and limit is greater than 48.88:以下操作将删除stock : "Brent Crude Futures"（布伦特原油期货）且limit大于48.88的所有文件：

try {
   db.orders.deleteMany( { "stock" : "Brent Crude Futures", "limit" : { $gt : 48.88 } } );
} catch (e) {
   print (e);
}

The operation returns:操作返回：

{ "acknowledged" : true, "deletedCount" : 8 }

deleteMany() with Write Concern带写入关注的deleteMany()

Given a three member replica set, the following operation specifies a w of majority and wtimeout of 100:给定一个由三个成员组成的复制集，以下操作指定w为majority，wtimeout为100：

try {
   db.orders.deleteMany(
       { "client" : "Crude Traders Inc." },
       { 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，则引发以下异常：

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.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.deleteMany(
   { 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.deleteMany(
   { "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" : 3 }

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。