MongoDB Guide (translation) (2)-developer zone-Introduction

 

Introduction

Mongodb is a set-oriented, flexible document-type database.

Collection-oriented means that data is stored in a data set called a collection group. Each set has a unique identification name in the database and can contain an infinite number of documents. The concept of a set is similar to that of a table in a relational database service (RDBMS). The difference is that it does not need to define any schema.

Schema-free means that we do not need to know any structure definition of a file stored in the mongodb database. If necessary, you can store files of different structures in the same database.

The so-called document refers to the document stored in the Set, which is stored as a key-value pair. Key is used to uniquely identify a document, which is a string type, and the value can be a variety of complex file types. We call this storage form BSON (Binary Serialized dOcument Format ).

 

MongoDB usage Overview

Mongodb is a server process that can run on linux, windows, and OS X. It can run as an application on a 32-bit or 64-bit operating system. Since mongo limits the total data size of all databases to 2 GB in 32-Bit mode, we recommend that you run it in 64-Bit mode.

The default listening port number of the mongodb process is 27017 (remind me that the port number can be set at startup. You can refer to "command line parameters" for more information ).

Connect the client to the server process (authentication is required if the security option is enabled) and perform continuous operations, such as insert, query, and update.

Mongodb stores data in files (the default path is/data/db/), and uses memory ing files for data management to improve efficiency.

Mongodb not only supports atomic data replication, but also supports atomic failover.

 

Mongodb features

Mongodb provides developers with a wide range of operations:

• Query: supports queries based on the query object or similar to SQL "where predicates ". You can sort the query results, set the number of returned results, skip some of the query results, and only return part of the content of the document.
• Insert and update: Insert a new document to update an existing document.
• Index management: Create an index that contains one or more keywords in the document. You can also use the substructure of the keyword to create an index or delete an index.
• Common commands: Any mongodb operation can be completed through the network using the DB command.