MongoDB Introduction and basic knowledge

About MongoDB

First, Mongdb is a high-performance, open-source, modeless document-type NoSQL database.
Main Features:
1. File storage format Bson (an extension of JSON)
2. Schema free, the data format is not limited the structure of the table
3. Support Dynamic Query
4. Full index support
5. Support Replication (its master-slave replication) and recovery
6. Use efficient binary data storage, including large objects
7. Automatically process fragmentation to support scaling at the cloud level.
8. Support for Java, Ruby, Python, C + +, PHP and many other languages
9. Internal JavaScript support


Second, the advantages of MongoDB
1. Fast query speed
2. High concurrency. Can reach 20,000 concurrent.
3. High capacity. The amount of data that supports 10TB meaning

Iii. MongoDB Usage Scenarios
1. Website data
2. Caching
3. Large-size, low-value data
4. High-stretch scene
5. For objects and JSON data storage


Iv. the shortcomings of MongoDB
1. Data greater than 2.5G is not supported on 32-bit operating systems
2. Single File size limit 16M
3. Highly transactional systems
4. Traditional Business intelligence applications


V. MONGODB and other database differences

Compare items	Mongodb (non-relational)	MySQL, Oracle (relational type)
Database	Databases (database)	Databases (database)
Table	Collection (collection)	Two-dimensional tables (table)
Recording	Documents (document)	Records (record)
Field	Keys (key)	Columns (column)
Primary FOREIGN Key	No	Pk, FK
Flexible scalability	Extremely high	Poor

According to its description, the results of MongoDB can be broadly summarized as:

Vi. MongoDB Data types
The following table is a few of the data types commonly used in MongoDB.

Data Type	Description
String	String. Data types commonly used to store data. In MongoDB, the UTF-8 encoded string is legal.
Integer	Integer value. Used to store numeric values. Depending on the server you are using, it can be divided into 32-bit or 64-bit.
Boolean	Boolean value. Used to store Boolean values (True/false).
Double	Double-precision floating-point value. Used to store floating-point values.
Min/max keys	Compares a value to the lowest and highest value of a BSON (binary JSON) element.
Array	Used to store an array or list or multiple values as a single key.
Timestamp	Time stamp. Record when the document was modified or added.
Object	Used for inline documents.
Null	Used to create a null value.
Symbol	Symbol. The data type is basically the same as the string type, but unlike it, it is typically used in languages with special symbol types.
Date	Date time. Use the UNIX time format to store the current date or time. You can specify your own datetime: Create a Date object and pass in the month-date information.
Object ID	The object ID. The ID used to create the document.
Binary Data	Binary data. Used to store binary data.
Code	The code type. Used to store JavaScript code in a document.
Regular expression	The regular expression type. Used to store regular expressions.

MongoDB Introduction and basic knowledge