Azure Classroomnotes 06/Dec/2022

Database Needs for Enterprise Applications

Every application needs data to be persisted.
Data can be persisted in majorly two forms
- structured data:
  - This data can be queried
  - To query the data there might be different means sql, reports, code
- unstructured:
  - This data cannot be queried
  - Data can be searched
This Data is further used by Analytics
- Business Intelligence => Reports
- Predictions (ML)
Through out discussion we would be focussing on structured data.
Database Types:
- Relational:
  - Data is organized as Rows and Columns in Tables
  - Releations exist across tables
  - To query the data we would be using SQL Specification
  - Each Table has a strict structure which is called as schema
  - Database Engines:
    - Oracle
    - Microsoft SQL Server
    - mySQL/mariadb
    - PostgreSQL
    - IBM DB2
- NoSQL:
  - To query the data there is no formal specification like SQL
  - There is no strict schema
  - There are different implemenations
    - document db
    - key value store
    - Graph db
  - Examples:
    - Mongo DB
    - Cassandra
    - etcd
    - consul
    - Gremlin
- Cache db:
  - Cache databases are designed to store infrequently changed data to RAM
  - Examples:
    - Redis
    - Memcached
- Data Warehouses:
  - This generally represents a large volumes of data warehouse and generally every record over here majorly has time dimension.
  - Examples:
    - Teradata
    - Informatica