AWS Classroomnotes 02/May/2023

Database

• Database is collection of information
• Database Management Systems are softwares/engines which allow multiple users to parallely work with data (Read/Write)
  • Read => Select
  • Write => Create/Update/insert
• Database types
  • Relational Databases
  • NOSQL Databases
  • Data Warehouse
    

Relational Database

• Relational Database are concept of Databases, where we design the data in terms of Tables with Rows and columns. The structure of the Table is called as Schema.
• Each row represents a record
• Tables will have relationships between them
  • one – one
  • one – many
  • many – one
  • many – many
    
• To work with databases a formal language called as SQL (Structure Query Language ) exists
• Popular Database Engines
  • Microsoft SQL Server
  • Oracle
  • mySQL
  • mariaDB
  • PostgreSql
  • DB2
• Databases are used from application code as well as db client software to deal with data
  
• Scaling helps in solving the needs as the usage grows
  • Vertical Scaling: increase hardware or system resources.
  • Horizontal Scaling: increase number of servers running databases
• Relational Databases donot have inbuilt support for horizontal scaling
• Replications need to be setup, for bidirectional transfers (DBA skills are required)
  
• Majority of the applications read more data than writing
  
• Administration:
  • Installation/Patching/Configuring
    • OS
    • DBMS
  • User Managment
  • Connection Management
  • Backups and recovery
  • Performance Tuning
  • Replications

NOSQL Databases

• NOSQL (Not only SQL) Databases are used to store semi structured information
• NOSQL Databases are designed to support
  • inbuilt horizontal scaling
  • semi-structured
  • don’t impose strict schema’s
• NOSQL Database Types
  • Key Value Stores
  • Document DB
  • Wide-Column Databases
  • Graph Databases