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Pre-Requisites

Database

  • DevOps engineers deploy and manage databases
  • SQL databases represent data in tabular format whereas noSQL databases represent data in documents.

MySQL

  • Open-source SQL database
  • Used by FaceBook and YouTube
  • yum install mysql-server - install MySQL on CentOS
  • systemctl start mysqld - start the MySQL service
  • Logs are available at /var/log/mysqld.log
    • When mysqld service is started, the logs contain a temporary password required to log into the MySQL database.
  • mysql -u root -p - login to the DB as root user (you will be prompted to enter password)
  • Commands
    • ALTER USER 'root'@'localhost' IDENTIFIED BY 'MyNewPassword' - change the password for root user
    • SHOW DATABASES
    • CREATE DATABASE Students
    • USE Students - Switch to Students database (can only work on 1 database at a time)
    • Once a DB is selected, you can create tables, insert values in them and so on...

User Management

  • Root users have admin access to the DB
  • Create additional users - CREATE USER 'john'@'localhost' IDENTIFIED BY 'password'
  • 'john'@'localhost' means that the user john can connect from the local host, he will be denied access if he tries to connect from another host.
  • 'john'@'192.168.1.10' means that the user john can connect from the host with IP 192.168.1.10
  • 'john'@'%' means that the user john can connect from any host
Assigning privileges to the users

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MongoDB

  • Open-source NoSQL database
  • Data is organized into documents
  • Multiple documents form a collection
  • Multiple collections form a database
  • We can have multiple databases within a MongoDB server
  • MongoDB is available as a cloud offering or as on-premises server
  • yum install mongodb-org
  • systemctl start mongod - start the MongoDB service
  • Logs are stored at /var/log/mongodb/mongod.1og
  • Configuration file is available at /etc/mongod.conf
  • Commands
    • mongo - activate mongo shell
    • show dbs - show databases
    • use school - switch to school DB (if not present, create new and switch)

Last updated: 2022-09-24