Introduction to NoSQL and MongoDB Installation on CentOS 7

NoSQL, short for "Not Only SQL", refers to non‑relational databases that have grown beyond the traditional SQL scope.

Compared with relational databases, NoSQL stores data in non‑tabular forms and offers several advantages:

Flexible data models

Horizontal scalability suitable for massive data storage

Fast retrieval without JOIN operations

Developer‑friendly

Non‑relational databases are generally divided into four categories:

Document databases

Key‑value stores

Wide‑column (wide‑table) databases

Graph databases

Among many NoSQL products, MongoDB is popular for its powerful features and ease of use. It is an open‑source distributed database that stores data as documents, making it the most relational‑like NoSQL system with a gentle learning curve.

MongoDB’s storage hierarchy consists of databases, collections, documents, and fields:

Field : a name‑value pair, similar to a column in a relational table.

Document : the basic data unit stored in BSON (binary JSON) format.

Collection : a group of documents, analogous to a table.

Database : a container for multiple collections, similar to a relational database.

To install MongoDB 7.0 on CentOS 7, you can use the yum repository. First, create the repository file:

vi /etc/yum.repos.d/mongodb-org-7.0.repo

Then add the following configuration:

[Mongodb-org-7.0]
name=MongoDB Repository
baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/7.0/x86_64/
gpgcheck=1
enabled=1
gpgkey=https://www.mongodb.org/static/pgp/server-7.0.asc

Install the packages:

sudo yum install -y mongodb-org

Alternatively, you can download the RPM files manually and install them:

rpm -ivh mongodb-org-server-7.0.2-1.el7.x86_64.rpm
rpm -ivh mongodb-org-mongos-7.0.2-1.el7.x86_64.rpm
rpm -ivh mongodb-mongosh-2.0.2.x86_64.rpm

After installation, run mongosh and execute show dbs to verify that MongoDB is working correctly.