MongoDB

• MongoDB is a document database designed for ease of development and scaling.

• MongoDB是一种文档数据库，设计用于简化开发和扩展。

• A record in MongoDB is a document, which is a data structure composed of field and value pairs. MongoDB documents are similar to JSON objects. The values of fields may include other documents, arrays, and arrays of documents.

• MongoDB中的记录是一个文档，它是一个由字段和值对组成的数据结构。MongoDB文档类似于JSON对象。字段的值可以包括其他文档、数组和文档数组。

 {
     name: "yang", // filed: value
     age: 26,
     status: "A",
     group: ["news", "sports"]
 }

• The advantages of using documents are:

  1. Documents (i.e. objects) correspond to native data types in many programming languages.
  2. Embedded documents and arrays reduce need for expensive joins.
  3. Dynamic schema supports fluent polymorphism.

• 使用文件的好处是:

1. 文档(即对象)对应于许多编程语言中的本地数据类型。
2. 嵌入的文档和数组减少了对昂贵连接的需求。
3. 动态模式支持连贯多态。

• MongoDB stores documents in collections.

• MongoDB将文档存储在集合中。

• Collections are analogous to tables in relational databases.

• 集合类似于关系数据库中的表。

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• Key Features High Performance MongoDB provides high performance data persistence. In particular,

• Support for embedded data models reduces I/O activity on database system. Indexes support faster queries and can include keys from embedded documents and arrays.

• Rich Query Language MongoDB supports a rich query language to support read and write operations (CRUD) as well as:

• Data Aggregation Text Search and Geospatial Queries. SEE ALSO

• SQL to MongoDB Mapping Chart

• SQL to Aggregation Mapping Chart Learn about the latest query language features with the MongoDB Query Language: What’s New presentation from MongoDB.live 2020. High Availability MongoDB’s replication facility, called replica set, provides:

• automatic failover

• data redundancy.

• A replica set is a group of MongoDB servers that maintain the same data set, providing redundancy and increasing data availability.

• Horizontal Scalability

• MongoDB provides horizontal scalability as part of its core functionality:

• Sharding distributes data across a cluster of machines.

• Starting in 3.4, MongoDB supports creating zones of data based on the shard key. In a balanced cluster, MongoDB directs reads and writes covered by a zone only to those shards inside the zone. See the Zones manual page for more information. Support for Multiple Storage Engines MongoDB supports multiple storage engines:

• WiredTiger Storage Engine (including support for Encryption at Rest)

• In-Memory Storage Engine.

• In addition, MongoDB provides pluggable storage engine API that allows third parties to develop storage engines for MongoDB.

• 关键特性

• 高性能

• MongoDB提供了高性能的数据持久性。特别是对嵌入式数据模型的支持减少了数据库系统上的I/O活动。

• 索引支持更快的查询，并且可以包含来自嵌入文档和数组的键。

• 丰富的查询语言

• MongoDB支持丰富的查询语言，支持读写操作(CRUD)，以及:

• 数据聚合

• 文本搜索和地理空间查询。

• 另请参阅

• SQL到MongoDB的映射图

• SQL到聚合映射图

• 了解MongoDB查询语言的最新查询语言特性:MongoDB的新表示。活2020年。

• 高可用性

• MongoDB的复制设施，称为replica set，提供:

• 自动故障转移

• 数据冗余。

• 副本集是一组MongoDB服务器，它们维护相同的数据集，提供冗余并增加数据可用性。

• 水平可伸缩性

• MongoDB提供了水平的可伸缩性作为其核心功能的一部分:

• 分片将数据分发到一个机器集群中。

• 从3.4开始，MongoDB支持基于shard key创建数据区域。在一个平衡的集群中，MongoDB只将一个区域覆盖的读和写定向到该区域内的那些碎片。有关更多信息，请参阅区域手册页。

• 支持多个存储引擎

• MongoDB支持多种存储引擎:

• WiredTiger存储引擎(包括支持静态加密)

• 内存存储引擎。 此外，MongoDB提供了可插拔的存储引擎API，允许第三方为MongoDB开发存储引擎。