A simple comparison of MongoDB and relational databases

MongoDB is a cross-platform, document-oriented database that provides high performance, high availability, and scalability convenience. MongoDB works on the concept of collection and documentation.

Database: A database is a collection of physical containers. Each database has its own set of files on the file system. A single MongoDB server typically has multiple databases.

Collection: A collection is a set of MongoDB documents. It is equivalent to an RDBMS table. The collection exists in a single database. The collection does not execute the pattern. The documents within the collection can have different areas. Typically, all files in a collection are of the same or related purpose.

Document: A document is a set of key-value pairs.

File dynamic mode. Dynamic mode refers to documents in the same collection that do not require a collection of common fields that have the same field or structure group, and can accommodate different types of data. The table given below shows RDBMS terminology using MongoDB relationships

_id is a 12-byte hexadecimal number that guarantees the uniqueness of each document.
You can provide _id to insert the document at the same time. If not provided, then each document of MongoDB provides a unique ID.
-id: "Example: _id:objectid (7df78ad8902c) Total 12 bytes"
The first 4 bytes are the current timestamp,
machine ID for the next 3 bytes,

mongodb Server and the remaining 3 bytes are simple increment values.