- $cmd
A special virtual collection that exposes MongoDB's database commands. 一个特殊的虚拟集合，公开MongoDB的数据库命令。To use database commands, see Issue Commands.要使用数据库命令，请参阅发布命令。- _id
A field required in every MongoDB document. 每个MongoDB文档中都需要一个字段。The _id field must have a unique value. _id字段必须具有唯一的值。You can think of the _id field as the document's primary key. 可以将_id字段视为文档的主键。If you create a new document without an _id field, MongoDB automatically creates the field and assigns a unique BSON ObjectId.如果创建一个没有_id字段的新文档，MongoDB会自动创建该字段并分配一个唯一的BSONObjectId。accumulator累加器An expression in an aggregation pipeline that maintains state between documents in the aggregation pipeline. 聚合管道中的一个表达式，用于维护聚合管道中文档之间的状态。For a list of accumulator operations, see $group.有关累加器操作的列表，请参阅$group。- action
An operation the user can perform on a resource. 用户可以对资源执行的操作。Actions and resources combine to create privileges. 操作和资源结合起来创建权限。See action.参阅操作。admin database数据库A privileged database. 权限数据库。Users must have access to the admin database to run certain administrative commands. 用户必须访问admin数据库才能运行某些管理命令。For a list of administrative commands, see Administration Commands.有关管理命令的列表，请参阅管理命令。aggregation聚合Any of a variety of operations that reduces and summarizes large sets of data. 减少和汇总大量数据的各种操作。MongoDB's aggregate() and mapReduce() methods are two examples of aggregation operations. MongoDB的aggregate()和mapReduce()方法是聚合操作的两个示例。For more information, see Aggregation.有关更多信息，请参阅聚合。aggregation pipeline聚合管道The set of MongoDB operators that let you calculate aggregate values without having to use map-reduce. MongoDB运算符集，允许您计算聚合值，而无需使用map-reduce。For a list of operators, see Aggregation Reference.有关运算符列表，请参阅聚合参考。- arbiter
A member of a replica set that exists solely to vote in elections. 仅为在选举中投票而存在的复制集的成员。Arbiters do not replicate data. 仲裁者不会复制数据。See Replica Set Arbiter.请参阅副本集仲裁器。- Atlas
- MongoDB Atlas
is a cloud-hosted database-as-a-service.是一个云托管的数据库即服务。
atomic operation原子操作An atomic operation is a write operation which either completes entirely, or does not complete at all. 原子操作是一种写操作，它要么完全完成，要么根本不完成。In the case of distributed transactions, which involve writes to multiple documents, all writes to each document must succeed for the transaction to succeed. 对于涉及写入多个文档的分布式事务，必须成功写入每个文档，事务才能成功。Atomic operations cannot partially complete. 原子操作不能部分完成。See Atomicity and Transactions.请参阅原子性和事务。authentication身份验证Verification of the user identity. 验证用户身份。See Authentication.请参阅身份验证。authorization授权Provisioning of access to databases and operations. 提供对数据库和操作的访问。See Role-Based Access Control.请参阅基于角色的访问控制。B-treeB-树A data structure commonly used by database management systems to store indexes. 数据库管理系统常用于存储索引的数据结构。MongoDB uses B-trees for its indexes.MongoDB使用B树作为索引。backup cursor备份游标A tailable cursor that points to a list of backup files. 指向备份文件列表的可裁剪游标。Backup cursors are for internal use only.备份游标仅供内部使用。balancer均衡器An internal MongoDB process that runs in the context of a sharded cluster and manages the migration of chunks. 一个内部MongoDB进程，在分片集群的上下文中运行，并管理块的迁移。Administrators must disable the balancer for all maintenance operations on a sharded cluster. 管理员必须为分片群集上的所有维护操作禁用均衡器。See Sharded Cluster Balancer.请参阅分片群集均衡器。- BSON
A serialization format used to store documents and make remote procedure calls in MongoDB. 一种序列化格式，用于在MongoDB中存储文档和进行远程过程调用。"BSON" is a portmanteau of the words "binary" and "JSON". “BSON”是“二进制”和“JSON”的组合。Think of BSON as a binary representation of JSON (JavaScript Object Notation) documents. 可以将BSON看作JSON(JavaScript对象表示法）文档的二进制表示。See BSON Types and MongoDB Extended JSON (v2).请参阅BSON类型和MongoDB扩展JSON(v2)。- BSON
types类型
The set of types supported by the BSON serialization format. BSON序列化格式支持的类型集。For a list of BSON types, see BSON Types.有关BSON类型的列表，请参阅BSON类型。CAP TheoremCAP定理Given three properties of computing systems, consistency, availability, and partition tolerance, a distributed computing system can provide any two of these features, but never all three.考虑到计算系统的三个属性：一致性、可用性和分区容限，分布式计算系统可以提供其中任意两个功能，但不能同时提供这三个功能。capped collection固定集合A fixed-sized collection that automatically overwrites its oldest entries when it reaches its maximum size. 一个固定大小的集合，当其达到最大大小时自动覆盖其最早的条目。The MongoDB oplog that is used in replication is a capped collection. 复制中使用的MongoDB oplog是一个有上限的集合。See Capped Collections.请参阅封顶集合。cardinality基数The measure of the number of elements within a set of values. 一组值中元素数量的度量。For example, the set A = { 2, 4, 6 } contains 3 elements, and has a cardinality of 3. 例如，集A = { 2, 4, 6 }包含3个元素，基数为3。See Shard Key Cardinality.请参见分片键基数。cartesian product笛卡尔积The result of combining two data sets such that the combined set contains every possible combination of values.组合两个数据集的结果，使得组合的数据集包含所有可能的值组合。- checksum
A calculated value used to ensure data integrity. 用于确保数据完整性的计算值。The md5 algorithm is sometimes used as a checksum.md5算法有时用作校验和。- chunk
A contiguous range of shard key values within a particular shard. Chunk ranges are inclusive of the lower boundary and exclusive of the upper boundary. 特定分片中分片键值的连续范围。区块范围包括下边界，不包括上边界。MongoDB splits chunks when they grow beyond the configured chunk size, which by default is 128 megabytes. MongoDB会在块超过配置的块大小（默认为128 MB）时拆分块。MongoDB migrates chunks when a shard contains too many chunks of a collection relative to other shards. 当一个分片包含的集合块相对于其他分片太多时，MongoDB会迁移块。See Data Partitioning with Chunks and Sharded Cluster Balancer.请参阅使用块进行数据分区和分片集群平衡器。- client
The application layer that uses a database for data persistence and storage. 使用数据库进行数据持久化和存储的应用层。Drivers provide the interface level between the application layer and the database server.驱动程序提供应用程序层和数据库服务器之间的接口级别。
Client can also refer to a single thread or process.客户端还可以引用单个线程或进程。
- cluster
See sharded cluster.请参阅分片群集。- collection
A grouping of MongoDB documents. MongoDB文档的分组。A collection is the equivalent of an RDBMS table. 集合相当于RDBMS表。A collection exists within a single database. 集合存在于单个数据库中。Collections do not enforce a schema. Documents within a collection can have different fields. 集合不强制架构。集合中的文档可以有不同的字段。Typically, all documents in a collection have a similar or related purpose. 通常，集合中的所有文档都有类似或相关的用途。See Namespaces.请参见命名空间。- collection scan
Collection scans are a query execution strategy where MongoDB must inspect every document in a collection to see if it matches the query criteria. 集合扫描是一种查询执行策略，MongoDB必须检查集合中的每个文档，看看它是否符合查询条件。These queries are very inefficient and do not use indexes. 这些查询效率很低，而且不使用索引。See Query Optimization for details about query execution strategies.有关查询执行策略的详细信息，请参阅查询优化。compound index复合指数An index consisting of two or more keys. 由两个或多个键组成的索引。See Compound Indexes.请参阅复合索引。concurrency control并发控制Concurrency control ensures that database operations can be executed concurrently without compromising correctness. 并发控制确保数据库操作可以在不影响正确性的情况下并发执行。Pessimistic concurrency control, such as used in systems with locks, will block any potentially conflicting operations even if they may not turn out to actually conflict. 悲观并发控制，例如在带锁的系统中使用的并发控制，将阻止任何潜在的冲突操作，即使它们可能不会实际发生冲突。Optimistic concurrency control, the approach used by WiredTiger, will delay checking until after a conflict may have occurred, aborting and retrying one of the operations involved in any write conflict that arises.WiredTiger使用的乐观并发控制方法将延迟检查，直到可能发生冲突之后，中止并重试出现的任何写入冲突中涉及的操作之一。config database配置数据库An internal database that holds the metadata associated with a sharded cluster. 一个内部数据库，保存与分片集群相关联的元数据。Applications and administrators should not modify the config database in the course of normal operation. 在正常操作过程中，应用程序和管理员不应修改config数据库。See Config Database.请参阅config数据库。config server配置服务器A mongod instance that stores all the metadata associated with a sharded cluster. 一个mongod实例，存储与分片集群关联的所有元数据。See Config Servers.请参阅配置服务器。connection pool连接池A cache of database connections maintained by the driver. 由驱动程序维护的数据库连接缓存。These connections are re-used when connections to the database are required, instead of opening new connections.当需要连接到数据库时，将重新使用这些连接，而不是打开新的连接。- container
A collected set of software and its dependent libraries that are packaged together to make transferring between computing environments easier. 一组集合的软件及其相关库，它们打包在一起，使计算环境之间的传输更容易。Containers run as compartmentalized processes on your operating system, and can be given their own resource constraints. 容器在您的操作系统上作为分隔的进程运行，并且可以被赋予它们自己的资源约束。Common container technologies are Docker and Kubernetes.常见的容器技术是Docker和Kubernetes。- CRUD
An acronym for the fundamental operations of a database: Create, Read, Update, and Delete. 数据库基本操作的缩写：创建、读取、更新和删除。See MongoDB CRUD Operations.请参阅MongoDB CRUD操作。- CSV
A text-based data format consisting of comma-separated values. 一种基于文本的数据格式，由逗号分隔的值组成。This format is commonly used to exchange data between relational databases since the format is well-suited to tabular data. 这种格式通常用于在关系数据库之间交换数据，因为这种格式非常适合表格数据。You can import CSV files using mongoimport.您可以使用mongoimport导入CSV文件。cursor游标A pointer to the result set of a query. 指向查询结果集的指针。Clients can iterate through a cursor to retrieve results. 客户机可以遍历游标来检索结果。By default, cursors not opened within a session automatically timeout after 10 minutes of inactivity. 默认情况下，会话中未打开的游标在不活动10分钟后自动超时。Cursors opened under a session close with the end or timeout of the session. 在会话结束或超时时关闭会话下打开的游标。See Iterate a Cursor in mongosh.请参见在mongosh中迭代游标。daemon守护进程The conventional name for a background, non-interactive process.非交互式后台进程的传统名称。data directory数据目录The file-system location where the mongod stores data files. mongod存储数据文件的文件系统位置。The dbPath option specifies the data directory.dbPath选项指定数据目录。data partition数据分区A distributed system architecture that splits data into ranges. 一种分布式系统架构，将数据划分为多个范围。Sharding uses partitioning. 分片使用分区。See Data Partitioning with Chunks.请参阅数据块分区。data-center awareness数据中心意识A property that allows clients to address members in a system based on their locations. 一种属性，允许客户端根据成员的位置向系统中的成员发送地址。Replica sets implement data-center awareness using tagging. 复制集使用标记实现数据中心感知。See Data Center Awareness.请参阅数据中心意识。database数据库A physical container for collections. 集合的物理容器。Each database gets its own set of files on the file system. 每个数据库在文件系统上都有自己的一组文件。A single MongoDB server typically has multiple databases.单个MongoDB服务器通常有多个数据库。database command数据库命令A MongoDB operation, other than an insert, update, remove, or query. MongoDB操作，而不是插入、更新、删除或查询。For a list of database commands, see Database Commands. 有关数据库命令的列表，请参阅数据库命令。To use database commands, see Issue Commands.要使用数据库命令，请参阅发出命令。database profiler数据库探查器A tool that, when enabled, keeps a record on all long-running operations in a database's system.profile collection. 一种工具，启用后，它会记录数据库的system.profile集合中所有长期运行的操作。The profiler is most often used to diagnose slow queries. 探查器最常用于诊断慢速查询。See Database Profiling.请参阅数据库分析。- dbpath
The location of MongoDB's data file storage. MongoDB数据文件存储的位置。See dbPath.请参见dbPath。delayed member延迟成员A replica set member that cannot become primary and applies operations at a specified delay. 副本集成员，不能成为主要成员，并以指定的延迟应用操作。The delay is useful for protecting data from human error (i.e. unintentionally deleted databases) or updates that have unforeseen effects on the production database. 延迟有助于保护数据不受人为错误（即无意中删除的数据库）或对生产数据库产生意外影响的更新的影响。See Delayed Replica Set Members.请参阅延迟副本集成员。document文档A record in a MongoDB collection and the basic unit of data in MongoDB. MongoDB集合中的记录和MongoDB中数据的基本单位。Documents are analogous to JSON objects but exist in the database in a more type-rich format known as BSON. 文档类似于JSON对象，但在数据库中以更富类型的格式存在，称为BSON。See Documents.请参阅文档。dot notation点记号法MongoDB uses the dot notation to access the elements of an array and to access the fields of an embedded document. MongoDB使用点符号来访问数组的元素和嵌入式文档的字段。See Dot Notation.请参阅点符号。draining排水The process of removing or "shedding" chunks from one shard to another. 将块从一个分片移到另一个分片的过程。Administrators must drain shards before removing them from the cluster. 管理员必须在将分片从群集中移除之前将其排出。See Remove Shards from an Existing Sharded Cluster.请参见从现有分片集群中删除分片。driver驱动程序A client library for interacting with MongoDB in a particular language. 用于以特定语言与MongoDB交互的客户端库。See driver.请参阅驱动程序。- durable
A write operation is durable when it will persist across a shutdown (or crash) and restart of one or more server processes. 当写入操作在一个或多个服务器进程的关闭（或崩溃）和重新启动期间持续时，写入操作是持久的。For a single mongod server, a write operation is considered durable when it has been written to the server's journal file. 对于单个mongod服务器，当写入操作已写入服务器的日志文件时，写入操作被认为是持久的。For a replica set, a write operation is considered durable once the write operation is durable on a majority of voting nodes; i.e. written to a majority of voting nodes' journals.对于副本集，一旦写入操作在大多数投票节点上是持久的，则写入操作被认为是持久的；即，写入大多数投票节点的日志。election选举The process by which members of a replica set select a primary on startup and in the event of a failure. 副本集的成员在启动时和发生故障时选择主副本的过程。See Replica Set Elections.请参见副本集选择。eventual consistency最终一致性A property of a distributed system that allows changes to the system to propagate gradually. 分布式系统的一种特性，允许对系统的更改逐渐传播。In a database system, this means that readable members are not required to reflect the latest writes at all times.在数据库系统中，这意味着可读成员不需要始终反映最新的写操作。- expression
In the context of an aggregation pipeline, expressions are the stateless transformations that operate on the data that passes through a pipeline. 在聚合管道的上下文中，表达式是对通过管道的数据进行操作的无状态转换。See Aggregation Pipeline.请参见聚合管道。failover故障转移The process that allows a secondary member of a replica set to become primary in the event of a failure. 允许副本集的辅助成员在发生故障时成为主成员的过程。See Automatic Failover.请参阅自动故障切换。field字段A name-value pair in a document. 文档中的名称-值对。A document has zero or more fields. Fields are analogous to columns in relational databases. 文档有零个或多个字段。字段类似于关系数据库中的列。See Document Structure.请参见文档结构。- field path
Path to a field in the document. 文档中某个字段的路径。To specify a field path, use a string that prefixes the field name with a dollar sign ($).要指定字段路径，请使用以美元符号（$）作为字段名前缀的字符串。- firewall
A system level networking filter that restricts access based on, among other things, IP address. 一种系统级网络筛选器，它根据IP地址等限制访问。Firewalls form a part of an effective network security strategy. 防火墙是有效网络安全策略的一部分。See Firewalls.请参见防火墙。- fsync
A system call that flushes all dirty, in-memory pages to disk. 一种系统调用，将所有脏的内存页刷新到磁盘。MongoDB calls fsync() on its database files at least every 60 seconds. MongoDB至少每60秒对其数据库文件调用一次fsync()。See fsync.请参阅fsync。- geohash
A geohash value is a binary representation of the location on a coordinate grid. geohash值是坐标网格上位置的二进制表示。See Calculation of Geohash Values for 2d Indexes.请参阅2d索引的Geohash值计算。- GeoJSON
A geospatial data interchange format based on JavaScript Object Notation (JSON). 基于JavaScript对象表示法（JSON）的地理空间数据交换格式。GeoJSON is used in geospatial queries. GeoJSON用于地理空间查询。For supported GeoJSON objects, see Geospatial Data. 有关支持的GeoJSON对象，请参阅地理空间数据。For the GeoJSON format specification, see https://tools.ietf.org/html/rfc7946#section-3.1.有关GeoJSON格式规范，请参阅https://tools.ietf.org/html/rfc7946#section-3.1。geospatial地理空间Relating to geographical location. 与地理位置有关。See Geospatial Queries.请参见地理空间查询。- GridFS
A convention for storing large files in a MongoDB database. 在MongoDB数据库中存储大型文件的约定。All of the official MongoDB drivers support this convention, as does the mongofiles program. 所有官方MongoDB驱动程序都支持此约定，mongofiles程序也是如此。See GridFS.请参见GridFS。hashed shard key哈希分片键A special type of shard key that uses a hash of the value in the shard key field to distribute documents among members of the sharded cluster. 一种特殊类型的分片键，它使用分片键字段中的值哈希在分片集群的成员之间分发文档。See Hashed Indexes.请参见散列索引。haystack index干草堆索引A geospatial index that enhances searches by creating "buckets" of objects grouped by a second criterion. See geoHaystack Indexes.一种地理空间索引，通过创建按第二个标准分组的对象的“桶”来增强搜索。参见geoHaystack索引。hidden member隐藏成员A replica set member that cannot become primary and are invisible to client applications. 无法成为primary的副本集成员，对客户端应用程序不可见。See Hidden Replica Set Members.查看隐藏的副本集成员。high availability高可用性High availability indicates a system designed for durability, redundancy, and automatic failover such that the applications supported by the system can operate continuously and without downtime for a long period of time. 高可用性表示一个为耐久性、冗余和自动故障切换而设计的系统，这样系统支持的应用程序可以连续运行，并且不会出现长时间的停机。MongoDB replica sets support high availability when deployed according to our documented best practices.MongoDB副本集在根据我们记录的最佳实践部署时支持高可用性。
For guidance on replica set deployment architecture, see Replica Set Deployment Architectures.有关副本集部署体系结构的指南，请参阅副本集部署架构。
idempotent幂等The quality of an operation to produce the same result given the same input, whether run once or run multiple times.在相同的输入下，无论是运行一次还是多次运行，都能产生相同结果的操作质量。index索引A data structure that optimizes queries. 优化查询的数据结构。See Indexes.请参见索引。init script初始化脚本A simple shell script used by a Linux platform's init system to start, restart, or stop a daemon process. Linux平台的init系统用于启动、重新启动或停止守护进程的简单shell脚本。If you installed MongoDB via a package manager, an init script has been provided for your system as part of the installation. 如果您通过软件包管理器安装MongoDB，则在安装过程中会为您的系统提供一个初始化脚本。See the respective Installation Guide for your operating system.请参阅相应的操作系统安装指南。- init
system系统
The init system is the first process started on a Linux platform after the kernel starts, and manages all other processes on the system. init系统是内核启动后在Linux平台上启动的第一个进程，它管理系统上的所有其他进程。The init system uses an init script to start, restart, or stop a daemon process, such as mongod or mongos. init系统使用init脚本启动、重新启动或停止守护进程，如mongod或mongos。Recent versions of Linux tend to use the systemd init system, which uses the systemctl command, while older versions tend to use the System V init system, which uses the service command. 最新版本的Linux倾向于使用systemd init系统，它使用systemctl命令，而较旧版本倾向于使用system V init系统，它使用service命令。See the respective Installation Guide for your operating system.请参阅相应的操作系统安装指南。- initial sync
The replica set operation that replicates data from an existing replica set member to a new replica set member. 将数据从现有副本集成员复制到新副本集成员的副本集操作。See Initial Sync.请参阅初始同步。- intent lock
A lock on a resource that indicates that the holder of the lock will read (intent shared) or write (intent exclusive) the resource using concurrency control at a finer granularity than that of the resource with the intent lock. 资源上的一种锁，表示锁的持有者将使用并发控制Intent locks allow concurrent readers and writers of a resource. 意图锁允许资源的并发读写器。See What type of locking does MongoDB use?.查看MongoDB使用哪种类型的锁定？。- interrupt point
A point in an operation's lifecycle when it can safely abort. 操作生命周期中可以安全中止的点。MongoDB only terminates an operation at designated interrupt points. MongoDB只在指定的中断点终止操作。See Terminate Running Operations.请参阅终止运行操作。- IPv6
A revision to the IP (Internet Protocol) standard that provides a significantly larger address space to more effectively support the number of hosts on the contemporary Internet.对IP(Internet协议）标准的修订，提供了更大的地址空间，以更有效地支持当代Internet上的主机数量。- ISODate
The international date format used by mongosh to display dates. mongosh用于显示日期的国际日期格式。The format is: YYYY-MM-DD HH:MM.SS.millis.格式为：YYYY-MM-DD HH:MM.SS.millis。- JavaScript
A popular scripting language originally designed for web browsers. 最初为web浏览器设计的流行脚本语言。mongosh, the legacy mongo shell, and certain server-side functions use a JavaScript interpreter. mongosh、传统mongo shell和某些服务器端函数使用JavaScript解释器。See Server-side JavaScript for more information.有关更多信息，请参阅服务器端JavaScript。- journal
A sequential, binary transaction log used to bring the database into a valid state in the event of a hard shutdown. 一种连续的二进制事务日志，用于在发生硬关闭时使数据库进入有效状态。Journaling writes data first to the journal and then to the core data files. 日志记录首先将数据写入日志，然后写入核心数据文件。MongoDB enables journaling by default for 64-bit builds of MongoDB version 2.0 and newer. 默认情况下，MongoDB为MongoDB 2.0版及更高版本的64位版本启用日志记录。Journal files are pre-allocated and exist as files in the data directory. 日志文件是预先分配的，并作为文件存在于数据目录中。See Journaling.请参阅日志记录。- JSON
JavaScript Object Notation. JavaScript对象表示法。A human-readable, plain text format for expressing structured data with support in many programming languages. 一种人类可读的纯文本格式，用于表达结构化数据，支持多种编程语言。For more information, see http://www.json.org. 有关更多信息，请参阅http://www.json.org。Certain MongoDB tools render an approximation of MongoDB BSON documents in JSON format. 某些MongoDB工具以JSON格式呈现MongoDB BSON文档的近似值。See MongoDB Extended JSON (v2).请参阅MongoDB扩展JSON(v2)。- JSON
document文档
A JSON document is a collection of fields and values in a structured format. JSON文档是结构化格式的字段和值的集合。For sample JSON documents, see http://json.org/example.html.有关示例JSON文档，请参阅http://json.org/example.html。- JSONP
JSON with Padding. 带填充的JSON。Refers to a method of injecting JSON into applications. 指将JSON注入应用程序的方法。Presents potential security concerns.提出潜在的安全问题。least privilege最小权限An authorization policy that gives a user only the amount of access that is essential to that user's work and no more.一种授权策略，该策略仅为用户提供对其工作至关重要的访问量，仅此而已。legacy coordinate pairs遗留坐标对The format used for geospatial data prior to MongoDB version 2.4. MongoDB 2.4版之前用于地理空间数据的格式。This format stores geospatial data as points on a planar coordinate system (e.g. [ x, y ]). 该格式将地理空间数据存储为平面坐标系上的点（例如[ x, y ]）。See Geospatial Queries.请参见地理空间查询。- LineString
A LineString is defined by an array of two or more positions. LineString由两个或多个位置的数组定义。A closed LineString with four or more positions is called a LinearRing, as described in the GeoJSON LineString specification:https://tools.ietf.org/html/rfc7946#section-3.1.4. 如GeoJSON LineString规范https://tools.ietf.org/html/rfc7946#section-3.1.4中所述，具有四个或更多位置的闭合LineString称为LinearRing：
To use a LineString in MongoDB, see GeoJSON Objects.要在MongoDB中使用LineString，请参阅GeoJSON对象。- lock
MongoDB uses locks to ensure that concurrency does not affect correctness. MongoDB使用锁来确保并发不会影响正确性。MongoDB uses read locks, write locks and intent locks. MongoDB使用读锁、写锁和意图锁。For more information, see What type of locking does MongoDB use?.有关更多信息，请参阅MongoDB使用的锁定类型？。- LVM
Logical volume manager. 逻辑卷管理器。LVM is a program that abstracts disk images from physical devices and provides a number of raw disk manipulation and snapshot capabilities useful for system management. LVM是一个从物理设备抽象磁盘映像的程序，它提供了许多原始磁盘操作和快照功能，可用于系统管理。For information on LVM and MongoDB, see Back Up and Restore Using LVM on Linux.有关LVM和MongoDB的信息，请参阅在Linux上使用LVM进行备份和恢复。- map-reduce
A data processing and aggregation paradigm consisting of a "map" phase that selects data and a "reduce" phase that transforms the data. 数据处理和聚合范例，包括选择数据的“映射”阶段和转换数据的“减少”阶段。In MongoDB, you can run arbitrary aggregations over data using map-reduce. 在MongoDB中，您可以使用map-reduce对数据运行任意聚合。For map-reduce implementation, see Map-Reduce. 有关map-reduce实现，请参阅Map-Reduce。For all approaches to aggregation, see Aggregation.有关聚合的所有方法，请参阅聚合。mapping type映射类型A Structure in programming languages that associate keys with values, where keys may nest other pairs of keys and values (e.g. dictionaries, hashes, maps, and associative arrays). 编程语言中的一种结构，将键与值相关联，其中键可以嵌套其他键和值对（例如字典、哈希、映射和关联数组）。The properties of these structures depend on the language specification and implementation. Generally the order of keys in mapping types is arbitrary and not guaranteed.这些结构的属性取决于语言规范和实现。通常，映射类型中键的顺序是任意的，并且不能保证。- md5
A hashing algorithm used to efficiently provide reproducible unique strings to identify and checksum data. 一种哈希算法，用于有效地提供可复制的唯一字符串以识别和校验和数据。MongoDB uses md5 to identify chunks of data for GridFS. MongoDB使用md5为 GridFS识别数据块。See filemd5.请参阅filemd5。- MIB
Management Information Base. 管理信息库。MongoDB uses MIB files to define the type of data tracked by SNMP in the MongoDB Enterprise edition.MongoDB使用MIB文件定义MongoDB企业版中SNMP跟踪的数据类型。- MIME
Multipurpose Internet Mail Extensions. 多用途Internet邮件扩展。A standard set of type and encoding definitions used to declare the encoding and type of data in multiple data storage, transmission, and email contexts. 一组标准的类型和编码定义，用于声明多个数据存储、传输和电子邮件上下文中数据的编码和类型。The mongofiles tool provides an option to specify a MIME type to describe a file inserted into GridFS storage.mongofiles工具提供了一个选项，可以指定MIME类型来描述插入到GridFS存储中的文件。- mongo
The legacy MongoDB shell. 传统MongoDB shell。The mongo process starts the legacy shell as a daemon connected to either a mongod or mongos instance. mongo进程将遗留shell作为连接到mongod或mongos实例的守护进程启动。The shell has a JavaScript interface.shell有一个JavaScript接口。
Starting in MongoDB v5.0, mongo is deprecated and mongosh replaces mongo as the client shell. 从MongoDB v5.0开始，mongo被弃用，mongosh取代mongo作为客户端shell。See mongosh.请参阅mongosh。
- mongod
The MongoDB database server. MongoDB数据库服务器。The mongod process starts the MongoDB server as a daemon. mongod进程将MongoDB服务器作为守护进程启动。The MongoDB server manages data requests and formats and manages background operations. MongoDB服务器管理数据请求、格式化和管理后台操作。See mongod.请参阅mongod。- mongos
The MongoDB sharded cluster query router. MongoDB分片集群查询路由器。The mongos process starts the MongoDB router as a daemon. mongos进程将MongoDB路由器作为守护进程启动。The MongoDB router acts as an interface between an application and a MongoDB sharded cluster and handles all routing and load balancing across the cluster. MongoDB路由器充当应用程序和MongoDB分片集群之间的接口，并处理集群中的所有路由和负载平衡。 See mongos.请参阅mongos。- mongosh
MongoDB Shell. MongoDB外壳。mongosh provides a shell interface to either a mongod or a mongos instance.mongosh为mongod或mongos实例提供了一个shell接口。
Starting in MongoDB v5.0, mongosh replaces mongo as the preferred shell.从MongoDB v5.0开始，mongosh取代mongo成为首选shell。
- namespace
The canonical name for a collection or index in MongoDB. MongoDB中集合或索引的规范名称。The namespace is a combination of the database name and the name of the collection or index, like so:[database-name].[collection-or-index-name]. 名称空间是数据库名称和集合或索引的名称的组合，例如：[database-name].[collection-or-index-name]。All documents belong to a namespace. 所有文档都属于一个命名空间。See Namespaces.请参阅名称空间。natural order自然秩序The order in which the database refers to documents on disk. 数据库引用磁盘上文档的顺序。This is the default sort order. 这是默认排序顺序。See $natural and Return in Natural Order.请参阅$natural和按自然顺序返回。network partition网络划分A network failure that separates a distributed system into partitions such that nodes in one partition cannot communicate with the nodes in the other partition.一种网络故障，将分布式系统划分为多个分区，使得一个分区中的节点无法与另一个分区的节点通信。
Sometimes, partitions are partial or asymmetric. 有时，分区是部分的或不对称的。An example of a partial partition would be a division of the nodes of a network into three sets, where members of the first set cannot communicate with members of the second set, and vice versa, but all nodes can communicate with members of the third set. 部分划分的示例是将网络的节点划分为三个集合，其中第一集合的成员不能与第二集合的成员通信，反之亦然，但所有节点都可以与第三集合的成员进行通信。In an asymmetric partition, communication may be possible only when it originates with certain nodes. 在非对称分区中，通信可能仅在源自某些节点时才可能。For example, nodes on one side of the partition can communicate to the other side only if they originate the communications channel.例如，分区一侧的节点只有在发起通信信道时才能与另一侧通信。
- ObjectId
A special 12-byte BSON type that guarantees uniqueness within the collection. 一种特殊的12字节BSON类型，保证集合中的唯一性。The ObjectId is generated based on timestamp, machine ID, process ID, and a process-local incremental counter. ObjectId基于时间戳、机器ID、进程ID和进程本地增量计数器生成。MongoDB uses ObjectId values as the default values for _id fields.MongoDB使用ObjectId值作为_id字段的默认值。operator运算符A keyword beginning with a $ used to express an update, complex query, or data transformation. 以$开头的关键字，用于表示更新、复杂查询或数据转换。For example, $gt is the query language's "greater than" operator. 例如，$gt是查询语言的“大于”运算符。For available operators, see Operators.有关可用的运算符，请参阅运算符。- oplog
A capped collection that stores an ordered history of logical writes to a MongoDB database. 一个封顶集合，用于存储对MongoDB数据库的逻辑写入的有序历史记录。The oplog is the basic mechanism enabling replication in MongoDB. oplog是在MongoDB中实现复制的基本机制。See Replica Set Oplog.请参阅Oplog的副本集。- optime
Changed in version 3.2.在版本3.2中更改。
The following describes the optime format used by protocolVersion: 1, introduced in MongoDB 3.2.下面描述了在MongoDB 3.2中引入的protocolVersion: 1使用的optime格式。
A reference to a position in the replication oplog. 对复制操作日志中位置的引用。The optime value is a document that contains:optime值是包含以下内容的文档：
ts, the Timestamp of the operation.，操作的时间戳。t, the term in which the operation was originally generated on the primary.，最初在主服务器上生成操作的term。
ordered query plan有序查询计划A query plan that returns results in the order consistent with the sort() order. 以与sort()顺序一致的顺序返回结果的查询计划。See Query Plans.请参阅查询计划。orphaned document孤立文档In a sharded cluster, orphaned documents are those documents on a shard that also exist in chunks on other shards as a result of failed migrations or incomplete migration cleanup due to abnormal shutdown.在分片集群中，孤立文档是分片上的那些文档，由于迁移失败或由于异常关闭导致迁移清理不完整，这些文档也存在于其他分片上的块中。
Starting in MongoDB 4.4, orphaned documents are cleaned up automatically after a chunk migration completes. 从MongoDB 4.4开始，在块迁移完成后自动清理孤立文档。You no longer need to run cleanupOrphaned to delete orphaned documents.您不再需要运行cleanupOrphaned来删除孤立文档。
passive member被动成员A member of a replica set that cannot become primary because its members[n].priority is 0. 由于其members[n].priority为0，因此无法成为主副本集的成员。See Priority 0 Replica Set Members.请参阅副本集成员的优先级0。- PID
A process identifier. UNIX-like systems assign a unique-integer PID to each running process. 进程标识符。类UNIX系统为每个正在运行的进程分配唯一的整数PID。You can use a PID to inspect a running process and send signals to it. 可以使用PID检查正在运行的进程并向其发送信号。See /proc File System.请参阅/proc文件系统。- pipe
A communication channel in UNIX-like systems allowing independent processes to send and receive data. 类UNIX系统中的一种通信信道，允许独立进程发送和接收数据。In the UNIX shell, piped operations allow users to direct the output of one command into the input of another.在UNIX shell中，管道操作允许用户将一个命令的输出引导到另一个命令输入。- pipeline
A series of operations in an aggregation process. 聚合过程中的一系列操作。See Aggregation Pipeline.请参阅聚合管道。- Point
A single coordinate pair as described in the GeoJSON Point specification: https://tools.ietf.org/html/rfc7946#section-3.1.2. GeoJSON点规范中描述的单个坐标对：https://tools.ietf.org/html/rfc7946#section-3.1.2。To use a Point in MongoDB, see GeoJSON Objects.要在MongoDB中使用点，请参阅GeoJSON对象。- Polygon
An array of LinearRing coordinate arrays, as described in the GeoJSON Polygon specification: https://tools.ietf.org/html/rfc7946#section-3.1.6. LinearRing坐标数组数组，如GeoJSON多边形规范中所述：https://tools.ietf.org/html/rfc7946#section-3.1.6。For Polygons with multiple rings, the first must be the exterior ring and any others must be interior rings or holes.对于具有多个环的多边形，第一个环必须是外环，其他环必须是内环或孔。
MongoDB does not permit the exterior ring to self-intersect. MongoDB不允许外环自相交。Interior rings must be fully contained within the outer loop and cannot intersect or overlap with each other. 内环必须完全包含在外环内，不能相互交叉或重叠。See GeoJSON Objects.请参阅GeoJSON对象。
- powerOf2Sizes
A per-collection setting that changes and normalizes the way MongoDB allocates space for each document, in an effort to maximize storage reuse and to reduce fragmentation. 一种按集合设置，用于更改和规范MongoDB为每个文档分配空间的方式，以最大限度地提高存储重用并减少分片。This is the default for TTL Collections. 这是TTL集合的默认值。See collMod.参阅collMod。- pre-splitting
An operation performed before inserting data that divides the range of possible shard key values into chunks to facilitate easy insertion and high write throughput. 在插入数据之前执行的一种操作，将可能的分片键值范围划分为块，以便于轻松插入和高写入吞吐量。In some cases pre-splitting expedites the initial distribution of documents in sharded cluster by manually dividing the collection rather than waiting for the MongoDB balancer to do so. 在某些情况下，预分割通过手动分割集合而不是等待MongoDB平衡器来加速分片集群中文档的初始分发。See Create Chunks in a Sharded Cluster.请参见在分片集群中创建块。prefix compression前缀压缩Reduces memory and disk consumption by storing any identical index key prefixes only once, per page of memory. 通过每页内存只存储一次相同的索引键前缀，减少了内存和磁盘消耗。See: Compression for more about WiredTiger's compression behavior.有关WiredTiger压缩行为的更多信息，请参阅：压缩。- primary
In a replica set, the primary is the member that receives all write operations. 在副本集中，primary是接收所有写操作的成员。See Primary.参见Primary。- primary key
A record's unique immutable identifier. 记录的唯一不可变标识符。In an RDBMS, the primary key is typically an integer stored in each row's id field. 在RDBMS中，主键通常是存储在每行id字段中的整数。In MongoDB, the _id field holds a document's primary key which is usually a BSON ObjectId.在MongoDB中，_id字段保存文档的主键，通常是BSON ObjectId。primary shard主分片The shard that holds all the un-sharded collections. 包含所有未分片集合的分片。See Primary Shard.请参阅主分片。priority优先级A configurable value that helps determine which members in a replica set are most likely to become primary. 一个可配置值，用于帮助确定副本集中哪些成员最有可能成为主成员。See members[n].priority.请参阅members[n].priority的优先级。privilege权限A combination of specified resource and actions permitted on the resource. 指定资源和资源上允许的操作的组合。See privilege.请参阅特权。projection投影A document given to a query that specifies which fields MongoDB returns in the result set. 提供给查询的文档，指定MongoDB在结果集中返回哪些字段。See Project Fields to Return from Query. 请参见要从查询返回的投影字段。For a list of projection operators, see Projection Operators.有关投影运算符的列表，请参阅投影运算符。query查询A read request. 读取请求。MongoDB uses a JSON-like query language that includes a variety of query operators with names that begin with a $ character. MongoDB使用了一种类似JSON的查询语言，其中包括以$字符开头的名称的各种查询运算符。In mongosh, you can issue queries using the db.collection.find() and db.collection.findOne() methods. 在mongosh中，可以使用db.collection.find()和db.collection.findOne()方法发出查询。See Query Documents.请参阅查询文档。query optimizer查询优化器A process that generates query plans. 生成查询计划的过程。For each query, the optimizer generates a plan that matches the query to the index that will return results as efficiently as possible. 对于每个查询，优化器生成一个将查询与索引匹配的计划，该计划将尽可能高效地返回结果。The optimizer reuses the query plan each time the query runs. If a collection changes significantly, the optimizer creates a new query plan. 每次查询运行时，优化器都重用查询计划。如果集合发生显著变化，优化器将创建一个新的查询计划。See Query Plans.请参阅查询计划。query shape查询形状A combination of query predicate, sort, projection, and collation. 查询谓词、排序、投影和排序规则的组合。The query shape allows MongoDB to identify logically equivalent queries and analyze their performance.查询形状允许MongoDB识别逻辑等价的查询并分析其性能。
For the query predicate, only the structure of the predicate, including the field names, are significant; the values in the query predicate are insignificant. 对于查询谓词，只有谓词的结构（包括字段名）是重要的；查询谓词中的值不重要。As such, a query predicate { type: 'food' } is equivalent to the query predicate { type: 'utensil' } for a query shape.因此，查询谓词{ type: 'food' }等同于查询形状的查询谓词{ type: 'utensil' }。
To help identify slow queries with the same query shape, starting in MongoDB 4.2, each query shape is associated with a queryHash. 为了帮助识别具有相同查询形状的慢速查询，从MongoDB 4.2开始，每个查询形状都与一个queryHash关联。The queryHash is a hexadecimal string that represents a hash of the query shape and is dependent only on the query shape.queryHash是一个十六进制字符串，表示查询形状的哈希，并且仅依赖于查询形状。
Note注意
As with any hash function, two different query shapes may result in the same hash value. 与任何哈希函数一样，两个不同的查询形状可能导致相同的哈希值。However, the occurrence of hash collisions between different query shapes is unlikely.但是，不同查询形状之间不太可能发生哈希冲突。
- RDBMS
Relational Database Management System. 关系数据库管理系统。A database management system based on the relational model, typically using SQL as the query language.基于关系模型的数据库管理系统，通常使用SQL作为查询语言。read concern读取关注Specifies a level of isolation for read operations. 指定读取操作的隔离级别。For example, you can use read concern to only read data that has propagated to a majority of nodes in a replica set. 例如，您可以使用“读取关注点”仅读取已传播到副本集中大多数节点的数据。See Read Concern.请参阅读取关注。read lock读锁A shared lock on a resource such as a collection or database that, while held, allows concurrent readers but no writers. 资源（如集合或数据库）上的共享锁，在保持时允许并发读写器，但不允许写入器。See What type of locking does MongoDB use?.查看MongoDB使用哪种类型的锁定？。read preference读首选项A setting that determines how clients direct read operations. Read preference affects all replica sets, including shard replica sets. 确定客户端如何指导读取操作的设置。读取首选项影响所有副本集，包括分片副本集。By default, MongoDB directs reads to primaries. 默认情况下，MongoDB将读取定向到primary。However, you may also direct reads to secondaries for eventually consistent reads. 但是，您也可以将读取指向二级，以便实现最终一致读取。See Read Preference.请参阅读首选项。recovering恢复A replica set member status indicating that a member is not ready to begin normal activities of a secondary or primary. Recovering members are unavailable for reads.一种副本集成员状态，指示成员尚未准备好开始辅助或主的正常活动。恢复成员不可用于读取。replica pairs复制对The precursor to the MongoDB replica sets.MongoDB复制集的前身。
Deprecated since version 1.6自1.6版以来已弃用.
replica set副本集A cluster of MongoDB servers that implements replication and automated failover. 实现复制和自动故障转移的MongoDB服务器集群。MongoDB's recommended replication strategy. MongoDB推荐的复制策略。See Replication.请参阅复制。replication复制A feature allowing multiple database servers to share the same data, thereby ensuring redundancy and facilitating load balancing. 允许多个数据库服务器共享相同数据的功能，从而确保冗余并促进负载平衡。See Replication.请参阅复制。replication lag复制滞后The length of time between the last operation in the primary's oplog and the last operation applied to a particular secondary. primary操作日志中的最后一个操作与应用于特定辅助操作的最后一次操作之间的时间长度。In general, you want to keep replication lag as small as possible. 通常，您希望将复制延迟保持得尽可能小。See Replication Lag.请参阅复制滞后。resident memory常驻存储器The subset of an application's memory currently stored in physical RAM. 当前存储在物理RAM中的应用程序内存的子集。Resident memory is a subset of virtual memory, which includes memory mapped to physical RAM and to disk.常驻内存是虚拟内存的子集，包括映射到物理RAM和磁盘的内存。resource资源A database, collection, set of collections, or cluster. 数据库、集合、集合集或群集。A privilege permits actions on a specified resource. 权限允许对指定资源执行操作。See resource.请参阅资源。role角色A set of privileges that permit actions on specified resources. 允许对指定资源执行操作的一组权限。Roles assigned to a user determine the user's access to resources and operations. 分配给用户的角色决定了用户对资源和操作的访问。See Security.请参阅安全。rollback回滚A process that reverts writes operations to ensure the consistency of all replica set members. 恢复写操作以确保所有副本集成员一致性的过程。See Rollbacks During Replica Set Failover.请参阅复制集故障转移期间的回滚。- secondary
A replica set member that replicates the contents of the master database. 复制主数据库内容的复制集成员。Secondary members may handle read requests, but only the primary members can handle write operations. 次要成员可以处理读取请求，但只有主要成员可以处理写入操作。See Secondaries.请参见次要。secondary index二级索引A database index that improves query performance by minimizing the amount of work that the query engine must perform to fulfill a query. 一种数据库索引，通过最小化查询引擎必须执行的工作量来提高查询性能。See Indexes.请参阅索引。seed list种子列表A seed list is used by drivers and clients (like mongosh) for initial discovery of the replica set configuration. 驱动程序和客户端（如mongosh）使用种子列表来初始发现副本集配置。Seed lists can be provided as a list of host:port pairs (see Standard Connection String Format or via DNS entries (see DNS Seed List Connection Format).种子列表可以作为host:port对的列表提供（请参阅标准连接字符串格式或通过DNS条目（请参阅DNS种子列表连接格式）。- set name
The arbitrary name given to a replica set. 复制集的任意名称。All members of a replica set must have the same name specified with the replSetName setting or the --replSet option.副本集的所有成员必须使用replSetName设置或--replSet选项指定的相同名称。shard分片A single mongod instance or replica set that stores some portion of a sharded cluster's total data set. 存储分片集群总数据集的一部分的单个mongod实例或副本集。In production, all shards should be replica sets. 在生产中，所有分片都应该是副本集。See Shards.请参见分片。shard key分片键The field MongoDB uses to distribute documents among members of a sharded cluster. MongoDB用于在分片集群成员之间分发文档的字段。See Shard Keys.请参见分片键。sharded cluster分片群集The set of nodes comprising a sharded MongoDB deployment. 包含分片MongoDB部署的节点集。A sharded cluster consists of config servers, shards, and one or more mongos routing processes. 分片集群由配置服务器、分片和一个或多个mongos路由进程组成。See Sharded Cluster Components.请参见分片群集组件。sharding分片A database architecture that partitions data by key ranges and distributes the data among two or more database instances. 一种数据库体系结构，它按键范围划分数据，并将数据分布在两个或多个数据库实例之间。Sharding enables horizontal scaling. 分片支持水平缩放。See Sharding.请参阅分片。shell helpershell辅助对象A method in mongosh that provides a more concise syntax for a database command. mongosh中的一种方法，为数据库命令提供更简洁的语法。Shell helpers improve the general interactive experience. Shell助手可以改善一般的交互体验。See mongosh Methods.见mongosh方法。single-master replication单主复制A replication topology where only a single database instance accepts writes. 仅单个数据库实例接受写入的复制拓扑。Single-master replication ensures consistency and is the replication topology employed by MongoDB. 单主机复制确保一致性，是MongoDB采用的复制拓扑。See Replica Set Primary.请参阅副本集Primary。- snappy
A compression/decompression library designed to balance efficient computation requirements with reasonable compression rates. 一种压缩/解压缩库，旨在平衡有效的计算需求和合理的压缩率。Snappy is the default compression library for MongoDB's use of WiredTiger. Snappy是MongoDB使用WiredTiger的默认压缩库。See Snappy and the WiredTiger compression documentation for more information.有关更多信息，请参阅Snappy和WiredTiger压缩文档。split拆分The division between chunks in a sharded cluster. 分片群集中块之间的划分。See Data Partitioning with Chunks.请参见使用区块进行数据分区。- SQL
Structured Query Language (SQL) is a common special-purpose programming language used for interaction with a relational database, including access control, insertions, updates, queries, and deletions. 结构化查询语言（SQL）是一种通用的专用编程语言，用于与关系数据库交互，包括访问控制、插入、更新、查询和删除。There are some similar elements in the basic SQL syntax supported by different database vendors, but most implementations have their own dialects, data types, and interpretations of proposed SQL standards. 不同数据库供应商支持的基本SQL语法中有一些类似的元素，但大多数实现都有自己的方言、数据类型和对建议的SQL标准的解释。Complex SQL is generally not directly portable between major RDBMS products. 复杂SQL通常不能在主要RDBMS产品之间直接移植。SQL is often used as metonym for relational databases.通常用作关系数据库的转喻。- SSD
Solid State Disk. 固态磁盘。A high-performance disk drive that uses solid state electronics for persistence, as opposed to the rotating platters and movable read/write heads used by traditional mechanical hard drives.一种高性能磁盘驱动器，它使用固态电子器件实现持久性，与传统机械硬盘驱动器使用的旋转盘片和可移动读/写头不同。- standalone
An instance of mongod that is running as a single server and not as part of a replica set. mongod的一个实例，作为单个服务器而不是副本集的一部分运行。To convert a standalone into a replica set, see Convert a Standalone to a Replica Set.要将单机转换为副本集，请参阅将单机转换成副本集。storage engine存储引擎The part of a database that is responsible for managing how data is stored and accessed, both in memory and on disk. 数据库的一部分，负责管理数据在内存和磁盘上的存储和访问方式。Different storage engines perform better for specific workloads. 不同的存储引擎对特定工作负载的性能更好。See Storage Engines for specific details on the built-in storage engines in MongoDB.有关MongoDB中内置存储引擎的具体详细信息，请参阅存储引擎。- storage order
- See natural order.
strict consistency严格一致性A property of a distributed system requiring that all members always reflect the latest changes to the system. 分布式系统的一种属性，要求所有成员始终反映系统的最新变化。In a database system, this means that any system that can provide data must reflect the latest writes at all times.在数据库系统中，这意味着任何能够提供数据的系统必须始终反映最新的写入。Subject Alternative Name主题替代名称Subject Alternative Name (SAN) is an extension of the X.509 certificate which allows an array of values such as IP addresses and domain names that specify which resources a single security certificate may secure.Subject Alternative Name(SAN)是X.509证书的扩展，它允许一组值（如IP地址和域名）来指定单个安全证书可以保护哪些资源。sync同步The replica set operation where members replicate data from the primary. 成员从primary复制数据的副本集操作。Sync first occurs when MongoDB creates or restores a member, which is called initial sync. 同步首先发生在MongoDB创建或恢复成员时，这称为初始同步。Sync then occurs continually to keep the member updated with changes to the replica set's data. 然后不断进行同步，以使成员随着副本集数据的更改而更新。See Replica Set Data Synchronization.请参阅副本集数据同步。- syslog
On UNIX-like systems, a logging process that provides a uniform standard for servers and processes to submit logging information. 在类UNIX系统上，为服务器和进程提交日志记录信息提供一致性标准的日志记录过程。MongoDB provides an option to send output to the host’s syslog system. MongoDB提供了一个选项，可以将输出发送到主机的syslog系统。See syslogFacility.请参阅syslogFacility。- tag
A label applied to a replica set member and used by clients to issue data-center-aware operations. 应用于副本集成员并由客户端用于发出数据中心感知操作的标签。For more information on using tags with replica sets, see the following sections of this manual: Read Preference Tag Sets.有关对副本集使用标记的更多信息，请参阅本手册的以下章节：阅读首选项标记集。
Changed in version 3.4.在版本3.4中更改。
In MongoDB 3.4, sharded cluster zones replace tags.在MongoDB 3.4中，分片集群区域替换标记。
tag set标记集A document containing zero or more tags.包含零个或多个标记的文档。tailable cursor可尾随游标For a capped collection, a tailable cursor is a cursor that remains open after the client exhausts the results in the initial cursor. 对于封顶集合，可尾随的游标是指在客户端耗尽初始游标中的结果后仍保持打开状态的游标。As clients insert new documents into the capped collection, the tailable cursor continues to retrieve documents.当客户端将新文档插入到capped集合中时，可跟踪游标会继续检索文档。- term
For the members of a replica set, a monotonically increasing number that corresponds to an election attempt.对于复制集的成员，对应于选举尝试的单调递增的数字。time series collection时间序列集合A collection that efficiently stores sequences of measurements over a period of time. 有效存储一段时间内的测量序列的集合。See Time Series Collections.请参见时间序列集合。- topology
The state of a deployment of MongoDB instances, including the type of deployment (i.e. standalone, replica set, or sharded cluster) as well as the availability of servers, and the role of each server (i.e. primary, secondary, config server, or mongos.)MongoDB实例的部署状态，包括部署类型（即独立、副本集或分片集群）、服务器可用性以及每个服务器的角色（即primary、secondary、配置服务器或mongos）- TSV
A text-based data format consisting of tab-separated values. 由制表符分隔的值组成的基于文本的数据格式。This format is commonly used to exchange data between relational databases, since the format is well-suited to tabular data. 这种格式通常用于在关系数据库之间交换数据，因为这种格式非常适合表格数据。You can import TSV files using mongoimport.您可以使用mongoimport导入TSV文件。- TTL
Stands for "time to live" and represents an expiration time or period for a given piece of information to remain in a cache or other temporary storage before the system deletes it or ages it out. 表示“生存时间”，表示给定信息在系统删除或老化之前保留在缓存或其他临时存储中的到期时间或期限。MongoDB has a TTL collection feature. MongoDB具有TTL集合功能。See Expire Data from Collections by Setting TTL.请参阅通过设置TTL使集合中的数据过期。unique index唯一索引An index that enforces uniqueness for a particular field across a single collection. 在单个集合中强制特定字段唯一性的索引。See Unique Indexes.请参见唯一索引。- unix epoch
January 1st, 1970 at 00:00:00 UTC. Commonly used in expressing time, where the number of seconds or milliseconds since this point is counted.1970年1月1日00:00:00 UTC。通常用于表示时间，其中计算从该点开始的秒数或毫秒数。unordered query plan无序查询计划A query plan that returns results in an order inconsistent with the sort() order. 返回结果的查询计划的顺序与sort()顺序不一致。See Query Plans.请参见查询计划。- upsert
An option for update operations; e.g. db.collection.updateOne(), db.collection.findAndModify(). 更新操作的选项；例如db.collection.updateOne()、db.collection.findAndModify()。If set to true, the update operation will either update the document(s) matched by the specified query or if no documents match, insert a new document. 如果设置为true，更新操作将更新指定查询匹配的文档，或者如果没有匹配的文档则插入新文档。The new document will have the fields indicated in the operation. 新文档将具有操作中指示的字段。See Insert a New Document if No Match Exists (Upsert).请参见如果不存在匹配项则插入新文档（Upsert）。virtual memory虚拟内存An application's working memory, typically residing on both disk and in physical RAM.应用程序的工作内存，通常驻留在磁盘和物理RAM中。- WGS84
The default reference system and geodetic datum that MongoDB uses to calculate geometry over an Earth-like sphere for geospatial queries on GeoJSON objects. MongoDB用于计算类地球球体上的几何图形的默认参考系统和大地测量基准，用于对GeoJSON对象进行地理空间查询。See the "EPSG:4326: WGS 84" specification: http://spatialreference.org/ref/epsg/4326/.- working set
The data that MongoDB uses most often.MongoDB最常用的数据。- write concern
Specifies whether a write operation has succeeded. 指定写入操作是否成功。Write concern allows your application to detect insertion errors or unavailable mongod instances. 写问题允许应用程序检测插入错误或不可用的多个实例。For replica sets, you can configure write concern to confirm replication to a specified number of members. 对于副本集，可以配置写问题以确认复制到指定数量的成员。See Write Concern.请参阅写入问题。- write conflict
A situation in which two concurrent operations, at least one of which is a write, attempt to use a resource in a way that would violate constraints imposed by a storage engine using optimistic concurrency control. 一种情况，其中两个并发操作（其中至少一个是写操作）试图以违反存储引擎使用乐观并发控制施加的约束的方式使用资源。MongoDB will transparently abort and retry one of the conflicting operations.MongoDB将透明地中止并重试其中一个冲突操作。write lock写锁An exclusive lock on a resource such as a collection or database. 资源（如集合或数据库）上的独占锁。When a process writes to a resource, it takes an exclusive write lock to prevent other processes from writing to or reading from that resource. 当一个进程写入一个资源时，它使用一个独占写锁来防止其他进程写入或读取该资源。For more information on locks, see FAQ: Concurrency.有关锁的更多信息，请参阅常见问题解答：并发。- writeBacks
The process within the sharding system that ensures that writes issued to a shard that is not responsible for the relevant chunk get applied to the proper shard. 分片系统中的一个过程，它确保向不负责相关块的分片发出的写入被应用到正确的分片。For related information, see What does writebacklisten in the log mean? and writeBacksQueued.有关相关信息，请参阅日志中的writebacklisten是什么意思？和writeBacksQueued。- zlib
A data compression library that provides higher compression rates at the cost of more CPU, compared to MongoDB's use of snappy. 一个数据压缩库，与MongoDB使用的snappy相比，它以更多的CPU为代价提供更高的压缩率。You can configure WiredTiger to use zlib as its compression library. 您可以将WiredTiger配置为使用zlib作为其压缩库。See http://www.zlib.net and the WiredTiger compression documentation for more information.有关详细信息请参阅http://www.zlib.net和WiredTiger压缩文档。- zone
A grouping of documents based on ranges of shard key values for a given sharded collection. 基于给定分片集合的分片键值范围的文档分组。Each shard in the sharded cluster can associate with one or more zones. 分片集群中的每个分片可以与一个或多个区域关联。In a balanced cluster, MongoDB directs reads and writes covered by a zone only to those shards inside the zone. 在平衡集群中，MongoDB只将区域覆盖的读写操作定向到区域内的分片。See the Zones manual page for more information.有关详细信息，请参阅区域手册页面。
Zones supersede functionality described by tags in MongoDB 3.2.区域取代MongoDB 3.2中标记描述的功能。
- zstd
New in version 4.2.在版本4.2中新增。
A data compression library that provides higher compression rates and lower CPU usage when compared to zlib.与zlib相比，数据压缩库提供更高的压缩率和更低的CPU使用率。