Database Manual / Reference / mongosh Methods / Cursors

cursor.addOption() (mongosh method方法)

Definition定义

cursor.addOption(flag)

Important

mongosh Method方法

This page documents a mongosh method. This is not the documentation for a language-specific driver, such as Node.js.本页记录了一种mongosh方法。这不是针对特定语言驱动程序（如Node.js）的文档。

For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.有关MongoDB API驱动程序，请参阅特定语言的MongoDB驱动程序文档。

Note

Deprecated since v3.2自v3.2以来已弃用

Starting in v3.2, the cursor.addOption() operator is deprecated in mongo. Use available cursor methods instead.从v3.2开始，mongo中不推荐使用cursor.addOption()运算符。请改用可用的游标方法。

Used to change query behavior by setting the flags listed below.用于通过设置下面列出的标志来更改查询行为。

The cursor.addOption() method has the following parameter:cursor.addOption()方法有以下参数：

Parameter参数Type类型Description描述
flagflagFor mongosh, you can use the cursor flags listed below. For the driver-specific list, see your driver documentation.对于mongosh，您可以使用下面列出的游标标志。有关特定于驱动程序的列表，请参阅驱动程序文档。

Compatibility兼容性

This method is available in deployments hosted in the following environments:此方法在以下环境中托管的部署中可用：

  • MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud：云中MongoDB部署的完全托管服务

Important

This command has limited support in all MongoDB Atlas clusters. For more information, see Unsupported Commands.此命令在所有MongoDB Atlas集群中的支持有限。有关详细信息，请参阅不支持的命令。

  • MongoDB Enterprise: The subscription-based, self-managed version of MongoDB：MongoDB的基于订阅的自我管理版本
  • MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB：MongoDB的源代码可用、免费使用和自我管理版本

Flags标记

mongosh provides several additional cursor flags to modify the behavior of the cursor.提供了几个额外的游标标志来修改游标的行为。

Flag标记Description描述
DBQuery.Option.tailableSets the cursor not to close once the last data is received, allowing the query to continue returning data added after the initial results were exhausted.设置游标在收到最后一个数据后不关闭，允许查询继续返回在初始结果用尽后添加的数据。
DBQuery.Option.slaveOkAllows querying of a replica secondary.允许查询副本辅助。
DBQuery.Option.noTimeoutPrevents the server from timing out idle cursors.防止服务器使空闲游标超时。
DBQuery.Option.awaitDataFor use with DBQuery.Option.tailable. Sets the cursor to block the query thread when no data is available and await data for a set time instead of immediately returning no data. The cursor returns no data only if the timeout expires.与DBQuery.Option.tailable一起使用。将游标设置为在没有数据可用时阻止查询线程，并在设定的时间内等待数据，而不是立即返回无数据。只有当超时到期时，游标才会返回任何数据。
DBQuery.Option.exhaustSets the cursor to return all data returned by the query at once rather than splitting the results into batches.将游标设置为一次返回查询返回的所有数据，而不是将结果拆分为批次。
DBQuery.Option.partialSets the cursor to return partial data from a query against a sharded cluster in which some shards do not respond rather than throwing an error.将游标设置为从针对分片集群的查询中返回部分数据，其中一些分片没有响应，而是抛出错误。

Example示例

The following example adds the DBQuery.Option.tailable flag and the DBQuery.Option.awaitData flag to ensure that the query returns a tailable cursor. 以下示例添加了DBQuery.Option.tailable标志和DBQuery.Option.awaitData标志，以确保查询返回可尾随游标。The sequence creates a cursor. After returning the full result set, it waits for the default interval of 1000 milliseconds so that it can capture and return additional data added during the query:该序列创建了一个游标。返回完整结果集后，它会等待默认的1000毫秒间隔，以便捕获并返回查询过程中添加的其他数据：

var t = db.myCappedCollection;
var cursor = t.find().addOption(DBQuery.Option.tailable).
                      addOption(DBQuery.Option.awaitData)

Warning

Adding incorrect wire protocol flags can cause problems and/or extra server load.添加不正确的有线协议标志可能会导致问题和/或额外的服务器负载。