在mongoDB中什么被视为文档? [英] What is considered as a document in mongoDB?

问题描述

过去两天我一直在学习mongoDb，我一直对文档及其限制以及如何克服这些限制感到困惑.文档和馆藏之间有什么区别.

I have been learning mongoDb for past two days,I've been confusing with documents and their limits,and how to overcome the limits.What is a differnce between documents and collection.

推荐答案

要将其与传统的RDBMS进行粗略比较:

To roughly compare it with a traditional RDBMS:

RDBMS        |            MongoDB
_________________________________________
Database     |            Database
Table        |            Collection
Tuple/Row    |            Document
column       |            Field
Primary Key  |            Primary Key (Default key _id provided by mongodb itself)

过程:

Database Server(Daemon process) and Client
Mysqld/Oracle        |            mongod
mysql/sqlplus        |            mongo

mongos是在分片和/或副本集方案中的负载平衡期间使用的mongo服务器.

mongos is the mongo server used during load balancing in a sharding and/or replica set scenario.

因此在mongodb中，数据库由文档集合组成，每个文档包含任意数量的键值对.

Hence in mongodb, database consists of collections of documents and each document contains any number of key value pairs.

同一集合中的不同文档可以具有不同数量和类型的键.您可以说它没有架构；最基本的部分是:一切都基于从哈希值或键的哈希索引中检索值.

Different documents in the same collection can have different number and type of keys. You can say its schema-less; at the most basic part: everything is based on retrieving values from hash values or hash indices of keys.

在文档中，键的值可以从普通原始数据类型(字符串，整数，二进制数据等)到文档和数组.

Within a document, keys can have values ranging from normal primitive datatypes(string, int, binary data etc) to documents and arrays.

对于文档限制大小，由于mongodb以二进制JSON(BSON)压缩格式存储数据，因此16 MB就足够了.同样，嵌入文档也不会与父文档分开存储，并且会被计入16 MB的限制内.以下是有关文档数量限制的更多链接:

As for the document limit size, 16 MB is sufficient as mongodb stores your data in Binary JSON (BSON) compressed format. Also embedded documents are not stored separately wrt the parent document and are counted within the 16 MB limit. Here are few more links on document limit:

最新更改的mongodb文档限制
文档限制
链接
决定因素
更多信息

latest change of mongodb document limit
doc limit
link
deciding factor
more info

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