System Collections系统集合
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Synopsis提要
MongoDB stores system information in collections that use the MongoDB将系统信息存储在使用<database>.system.* namespace, which MongoDB reserves for internal use. Do not create collections that begin with system.<database>.system.*命名空间的集合中，MongoDB保留该命名空间供内部使用。不要创建以system开头的集合。
MongoDB also stores some additional instance-local metadata in the local database, specifically for replication purposes and in the config database for sessions information.MongoDB还在本地数据库中存储一些额外的实例本地元数据，专门用于复制目的，并在配置数据库中存储会话信息。
Collections集合
System collections include these collections stored in the 系统集合包括存储在admin database:admin数据库中的以下集合：
admin.system.roles-
Theadmin.system.rolescollection stores custom roles that administrators create and assign to users to provide access to specific resources.admin.system.roles集合存储管理员创建并分配给用户的自定义角色，以提供对特定资源的访问权限。
admin.system.users-
Theadmin.system.userscollection stores the user's authentication credentials as well as any roles assigned to the user.admin.system.users集合存储用户的身份验证凭据以及分配给用户的任何角色。Users may define authorization roles in the用户可以在admin.system.rolescollection.admin.system.roles集合中定义授权角色。
admin.system.version-
Theadmin.system.versioncollection stores metadata to support internal operations.admin.system.version集合存储元数据以支持内部操作。Do not modify this collection unless specifically instructed to in this documentation or by a MongoDB support engineer.除非本文档或MongoDB支持工程师特别指示，否则不要修改此集合。
System collections include these collections stored in the 系统集合包括存储在config database:config数据库中的以下集合：
config.system.indexBuildsNew in version 4.4.4.4版新增。TheindexBuildscollection stores information related to in-progress index builds.indexBuilds集合存储与正在进行的索引生成相关的信息。
Database-Specific Collections数据库特定集合
System collections also include these collections stored directly in each database:系统集合还包括直接存储在每个数据库中的这些集合：
<database>.system.buckets-
Stores the underlying data associated to a time series collection.存储与时间序列集合关联的基础数据。Thesystem.bucketscollection stores data in an optimized format and schema for an efficient representation of the persisted time series data.system.buckets集合以优化的格式和模式存储数据，以便有效地表示持久化的时间序列数据。Do not modify this collection.请勿修改此集合。
<database>.system.namespaces- Note
Removed in 4.2
Starting in MongoDB 4.2,从MongoDB 4.2开始，<database>.system.namespaceshas been removed (access to the collection has been deprecated since 3.0).<database>.system.namespaces系统名称空间已被删除（自3.0以来，对该集合的访问已被弃用）。To list the collections in a database, use the若要列出数据库中的集合，请改用listCollectionscommand instead.listCollections命令。
<database>.system.indexes- Note
Removed in 4.2
Starting in MongoDB 4.2,从MongoDB 4.2开始，<database>.system.indexeshas been removed (access to the collection has been deprecated since 3.0).<database>.system.indexes系统索引已被删除（自3.0以来，对该集合的访问已被弃用）。To list the indexes, use the若要列出索引，请改用listIndexescommand instead.listIndexes命令。
<database>.system.profile-
The<database>.system.profilecollection stores database profiling information.<database>.system.profile集合存储数据库分析信息。For information on profiling, see Database Profiling.有关分析的信息，请参阅数据库分析。
<database>.system.js-
The<database>.system.jscollection stores special JavaScript code for use in server side JavaScript.<database>.system.js集合存储用于服务器端JavaScript的特殊JavaScript代码。See Store a JavaScript Function on the Server for more information.有关详细信息，请参阅在服务器上存储JavaScript函数。
<database>.system.views-
The<database>.system.viewscollection contains information about each view in the database.<database>.system.views集合包含有关数据库中每个视图的信息。Starting in MongoDB 5.0, for featureCompatibilityVersion set to从MongoDB 5.0开始，对于设置为“5.0”或更高版本的"5.0"or greater, users can no longer write directly to the<database>.system.viewscollection.featureCompatibilityVersion，用户不能再直接写入<database>.system.views集合。