Introduction to MongoDB data types

Refer to MongoDB website: https://docs.mongodb.com/manual/reference/bson-types/

The MongoDB document store is using the BSON type, BSON (BSON short for bin-ary JSON, is a bin-ary-en-coded seri-al-iz-a-tion of Json-like Doc-u-men TS) is a binary serialization format. Classes, such as JSON, also support inline various types.

　　

Number

Type		Alias	Notes
Double	1	"Double"
String	2	"String"
Object	3	"Object"
Array	4	"Array"
Binary data	5	"Bindata"
Undefined	6	"Undefined"	Deprecated.
ObjectId	7	"ObjectId"
Boolean	8	"BOOL"
Date	9	"Date"
Null	10	"NULL"
Regular Expression	11	"Regex"
Dbpointer	12	"Dbpointer"	Deprecated.
Javascript	13	"JavaScript"
Symbol	14	"Symbol"	Deprecated.
JavaScript (with scope)	15	"Javascriptwithscope"
32-bit integer	16	"Int"
Timestamp	17	"Timestamp"
64-bit integer	18	"Long"
Decimal128	19	"Decimal"	New in version 3.4.
Min Key	-1	"Minkey"
Max Key	127	"Maxkey"

Several types are highlighted,

Objectid type: This is the only key that MongoDB generates like a relational DB table primary key, generating fast. This is made up of 12 bytes:

The first 4 bytes are unix seconds, 3 bytes of machine identifiers (for distributed primary keys are unique), 2 bytes of process id,3 bytes of counter number

• A 4-byte value representing the seconds since the Unix epoch,
• A 3-byte machine identifier,
• A 2-byte process ID, and
• A 3-byte counter, starting with a random value.

MongoDB was designed to be a distributed database. From the generation of the Objectid unique primary key, it deserves the reference of the Distributed System Designer.

A 3-byte machine identifier representing the different machine on which the MongoDB instance resides, and a 2-byte process ID representing a different MongoDB instance of the same machine. Plus a timestamp and a random number (3 bytes random number, the same second, theoretically can have 2^24), to a large extent, to ensure the uniqueness of the Objectid.

Introduction to MongoDB data types