Module 02 · Introducing MongoDB: An Open-Source NoSQL Database

Glossary: Getting Started with MongoDB术语表：MongoDB 入门

Welcome! This alphabetized glossary contains many of the terms you'll find within this course. This comprehensive glossary also includes additional industry-recognized terms not used in course videos. These terms are important for you to recognize when working in the industry, participating in user groups, and participating in other certificate programs.
欢迎！这个按字母顺序排列的术语表包含了您在本课程中会发现的大量术语。这个全面的术语表还包括了课程视频中未使用的、行业认可的术语。这些术语对于您在行业内工作、参与用户组以及参与其他认证项目时都非常重要。

Term 术语	Definition 定义
Aggregation pipeline 聚合管道	The aggregation pipeline in MongoDB allows for data transformation and processing using a series of stages, including filtering, grouping, sorting, and projecting. The aggregation pipeline is a powerful tool for expressive data manipulation. MongoDB 中的聚合管道允许使用一系列阶段对数据进行转换和处理，包括过滤、分组、排序和投影。聚合管道是表达数据操作功能强大的工具。
B+ Tree B+树	The B+ Tree is a data structure commonly used in database indexing to efficiently store and retrieve data based on ordered keys. B+树是一种常用于数据库索引的数据结构，能够基于有序键高效地存储和检索数据。
CRUD	CRUD is an acronym for create, read, update, and delete, which are the basic operations for interacting with and manipulating data in a database. CRUD 是创建（create）、读取（read）、更新（update）和删除（delete）的缩写，这些是数据库中与数据交互和操作的基本操作。
Election 选举	In a MongoDB replica set, an election is the process of selecting a new primary node when the current primary becomes unavailable. 在 MongoDB 副本集中，选举是指当当前主节点不可用时，选择一个新的主节点的过程。
Horizontal scaling 水平扩展	The process of adding more machines or nodes to a NoSQL database to improve its performance and capacity. This is typically achieved through techniques like sharding. 向 NoSQL 数据库添加更多机器或节点以提升其性能和容量的过程。这通常通过分片等技术实现。
Idempotent changes 幂等变更	Idempotent operations are those that can be safely repeated multiple times without changing the result. MongoDB encourages idempotent operations to ensure data consistency. 幂等操作是指可以安全地重复多次而不改变结果的操作。MongoDB 鼓励使用幂等操作以确保数据一致性。
Indexing 索引	The creation of data structures that improve query performance by allowing the database to quickly locate specific records based on certain fields or columns. 创建数据结构，通过允许数据库根据特定字段或列快速定位特定记录来提高查询性能。
Mongo shell	The MongoDB shell, known as mongo shell, is an interactive command-line interface that allows users to interact with a MongoDB server using JavaScript-like commands. The mongo shell is a versatile tool for administration and data manipulation. MongoDB shell，简称 mongo shell，是一个交互式命令行界面，允许用户使用类似 JavaScript 的命令与 MongoDB 服务器进行交互。Mongo shell 是一个用于管理和数据操作的通用工具。
MongoClient	MongoClient is the official MongoDB driver that provides a connection to a MongoDB server and allows developers to interact with the database in various programming languages. MongoClient 是 MongoDB 的官方驱动程序，它提供与 MongoDB 服务器的连接，并允许开发者在各种编程语言中与数据库进行交互。
Oplog	The Oplog is a special collection that records all write operations in a primary node. It is used to replicate data to secondary nodes and recover from failures. Oplog 是一个特殊的集合，用于记录主节点中的所有写操作。它用于将数据复制到从节点以及从故障中恢复。
Primary node 主节点	In a MongoDB replica set, the primary node is the active, writable node that processes all write operations. 在 MongoDB 副本集中，主节点是活跃的可写节点，处理所有写操作。
Replication 复制	Replication involves creating and maintaining copies of data on multiple nodes to ensure data availability, reduce data loss, fault tolerance (improve system resilience), and provide read scalability. 复制涉及在多个节点上创建和维护数据副本，以确保数据可用性、减少数据丢失、容错性（提高系统弹性）以及提供读扩展性。
Replication lag 复制延迟	Replication lag refers to the delay in data replication from a primary node to its secondary nodes in a replica set. Replication lag can impact the consistency of secondary data. 复制延迟是指主节点向副本集中的次节点复制数据时的延迟。复制延迟会影响次节点数据的 consistency。
Secondary 从节点	Secondary nodes replicate data from the primary and can be used for read-operations. 次节点从主节点复制数据，可用于读操作。
Sharding 分片	Refers to the practice of partitioning a database into smaller, more manageable pieces called shards to distribute data across multiple servers. Sharding helps with horizontal scaling. 指将数据库划分为更小、更易于管理的片段，称为分片，以将数据分布在多个服务器上。分片有助于水平扩展。
Vertical scaling 纵向扩展	Vertical scaling involves upgrading the resources (For example, CPU and RAM) of existing machines to improve performance. 纵向扩展涉及升级现有机器的资源（例如 CPU 和 RAM）以提高性能。