db.collection.dropIndexes()

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Definition定义

db.collection.dropIndexes()
Important重要
mongosh Method

This is a mongosh method. This is not the documentation for Node.js or other programming language specific driver methods.

In most cases, mongosh methods work the same way as the legacy mongo shell methods. However, some legacy methods are unavailable in mongosh.

For the legacy mongo shell documentation, refer to the documentation for the corresponding MongoDB Server release:

For MongoDB API drivers, refer to the language specific MongoDB driver documentation.

Drops the specified index or indexes (except the index on the _id field) from a collection.从集合中删除指定的索引（_id字段上的索引除外）。

You can use the method to:您可以使用该方法：

  • Drop all but the _id index from a collection.从集合中除去_id索引以外的所有索引。

    db.collection.dropIndexes()

  • Drop a specified index from a collection. 从集合中删除指定的索引。To specify the index, you can pass the method either:要指定索引，可以传递该方法：

    • The index specification document (unless the index is a text index in which case, use the index name to drop):索引规范文档（除非索引是text索引，否则请使用索引名称删除）：

      db.collection.dropIndexes( { a: 1, b: 1 } )

    • The index name:索引名称：

      db.collection.dropIndexes( "a_1_b_1" )
      Tip提示

      To get the names of the indexes, use the db.collection.getIndexes() method.要获取索引的名称，请使用db.collection.getIndexes()方法。

  • Drop specified indexes from a collection. (Available starting in MongoDB 4.2). 从集合中删除指定的索引。（从MongoDB 4.2开始提供）。To specify multiple indexes to drop, pass the method an array of index names:要指定要删除的多个索引，请向方法传递一个索引名称数组：

    db.collection.dropIndexes( [ "a_1_b_1", "a_1", "a_1__id_-1" ] )

    If the array of index names includes a non-existent index, the method errors without dropping any of the specified indexes.如果索引名称数组包含不存在的索引，则该方法会出错，但不会删除任何指定的索引。

    Tip提示

    To get the names of the indexes, use the db.collection.getIndexes() method.要获取索引的名称，请使用db.collection.getIndexes()方法。

The db.collection.dropIndexes() method takes the following optional parameter:db.collection.dropIndexes()方法采用以下可选参数：

Parameter参数Type类型Description描述
indexesstring or document or array of strings

Optional. 可选。Specifies the index or indexes to drop.指定要删除的一个或多个索引。

To drop all but the _id index from the collection, omit the parameter.要从集合中除去_id索引以外的所有索引，请省略该参数。

To drop a single index, specify either the index name, the index specification document (unless the index is a text index), or an array of the index name. 要删除单个索引，请指定索引名称、索引规范文档（除非索引是text索引）或索引名称的数组。To drop a text index, specify the index name or an array of the index name instead of the index specification document.要删除text索引，请指定索引名或索引名数组，而不是索引规范文档。

To drop multiple indexes (Available starting in MongoDB 4.2), specify an array of the index names.要删除多个索引（从MongoDB4.2开始可用），请指定一个索引名称数组。

The db.collection.dropIndexes() is a wrapper around the dropIndexes command.db.collection.dropIndexes()是dropIndexes命令的包装器。

Behavior行为

Starting in MongoDB 5.2, you can use db.collection.dropIndexes() to drop existing indexes on the same collection even if there is a build in progress on another index. 从MongoDB 5.2开始，您可以使用db.collection.dropIndexes()删除同一集合上的现有索引，即使另一个索引上正在进行构建。In earlier versions, attempting to drop a different index during an in-progress index build results in a BackgroundOperationInProgressForNamespace error.在早期版本中，在进行索引生成期间尝试删除其他索引会导致BackgroundOperationInProgressForNamespace错误。

Kill related queries only仅终止相关查询

Starting in MongoDB 4.2, the dropIndexes() operation only kills queries that are using the index being dropped. 从MongoDB 4.2开始，dropIndexes()操作仅终止使用被删除索引的查询。This may include queries considering the index as part of query planning.这可能包括将索引视为查询计划的一部分的查询。

Prior to MongoDB 4.2, dropping an index on a collection would kill all open queries on the collection.在MongoDB 4.2之前，删除集合上的索引会杀死集合上所有打开的查询。

Resource Locking资源锁定

Changed in version 4.2.在版本4.2中更改。

db.collection.dropIndexes() obtains an exclusive lock on the specified collection for the duration of the operation. 在操作期间获取指定集合的独占锁。All subsequent operations on the collection must wait until db.collection.dropIndexes() releases the lock.集合上的所有后续操作必须等待db.collection.dropIndexes()释放锁。

Prior to MongoDB 4.2, db.collection.dropIndexes() obtained an exclusive lock on the parent database, blocking all operations on the database and all its collections until the operation completed.在MongoDB 4.2之前，db.collection.dropIndexes()获得了父数据库的独占锁，阻止了数据库及其所有集合上的所有操作，直到操作完成。

Index Names索引名称

If the method is passed an array of index names that includes a non-existent index, the method errors without dropping any of the specified indexes.如果向该方法传递了一个包含不存在索引的索引名数组，则该方法会出错，并且不会删除任何指定的索引。

_id Index索引

You cannot drop the default index on the _id field.不能删除_id字段上的默认索引。

text Indexes文本索引

To drop a text index, specify the index name instead of the index specification document.要删除text索引，请指定索引名称而不是索引规范文档。

Stop In-Progress Index Builds停止进行中索引生成

Starting in MongoDB 4.4, if an index specified to db.collection.dropIndexes() is still building, db.collection.dropIndexes() attempts to stop the in-progress build. 从MongoDB 4.4开始，如果指定给db.collection.dropIndexes()的索引仍在构建中，db.collection.dropIndexes()会尝试停止正在进行的构建。Stopping an index build has the same effect as dropping the built index. 停止索引生成与删除生成的索引具有相同的效果。In versions earlier than MongoDB 4.4, db.collection.dropIndexes() returns an error if there are any index builds in progress on the collection.在MongoDB 4.4之前的版本中，如果集合上正在进行任何索引构建，db.collection.dropIndexes()将返回错误。

For replica sets, run db.collection.dropIndexes() on the primary. 对于副本集，请在主副本集上运行db.collection.dropIndexes()。The primary stops the index build and creates an associated "abortIndexBuild" oplog entry. 主节点停止索引构建并创建关联的“abortIndexBuild”oplog条目。Secondaries which replicate the "abortIndexBuild" oplog entry stop the in-progress index build and discard the build job. 复制“abortIndexBuild”oplog条目的秒停止正在进行的索引构建并放弃构建作业。See Index Build Process for detailed documentation on the index build process.有关索引生成过程的详细文档，请参阅索引生成过程。

Use currentOp to identify the index builds associated with a createIndexes or db.collection.createIndexes() operation. 使用currentOp标识与createIndexes或db.collection.createIndexes()操作关联的索引构建。See Active Indexing Operations for an example.有关示例，请参阅活动索引操作。

Hidden Indexes隐藏索引

Starting in version 4.4, MongoDB adds the ability to hide or unhide indexes from the query planner. 从4.4版开始，MongoDB添加了在查询计划程序中隐藏或取消隐藏索引的功能。By hiding an index from the planner, users can evaluate the potential impact of dropping an index without actually dropping the index.通过向计划者隐藏索引，用户可以评估删除索引的潜在影响，而无需实际删除索引。

If after the evaluation, the user decides to drop the index, the user can drop the hidden index; i.e. you do not need to unhide it first to drop it.如果在评估后，用户决定删除索引，则用户可以删除隐藏的索引；也就是说，您不需要先取消隐藏它就可以放下它。

If, however, the impact is negative, the user can unhide the index instead of having to recreate a dropped index. 但是，如果影响是负面的，用户可以取消隐藏索引，而不必重新创建删除的索引。And because indexes are fully maintained while hidden, the indexes are immediately available for use once unhidden.由于索引在隐藏时得到了完全维护，因此一旦取消隐藏，索引就可以立即使用。

For more information on hidden indexes, see Hidden Indexes.有关隐藏索引的详细信息，请参阅隐藏索引。

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