Thread by @swapnakpanda

SQL and NoSQL : Details & Key Differences

BONUS 💡: Which one is for you?

⇩

➊ What is a Database?
➋ What is a Relational Database?
➌ What is SQL?
➍ What is NoSQL?
➎ Categories
➏ SQL vs NoSQL
➐ BONUS: Which one is for you?

➊ What is a Database?

⬘ A database is an organised collection of data stored in a computer system (typically a server machine, but can be any machine) so that it can be accessed and managed easily.

⬗ In early days, each database had a separate way of data management. The way one database was storing and managing data may vary from another.

⬙ But with time this practice got normalised. The "Relational Database" design came into picture.

➋ What is a Relational Database?

⬘ A relational database is a "collection of data items" that have some "pre-defined relationships" between them.

⬗ Typically these items are organised as a set of "Tables" with "Columns" and "Rows".

⬙ Relationship between 2 tables are established based on one or multiple similar columns.

⬖ Relational databases grew in popularity. As so many of them exist, the need to develop one common language for managing both data and structures became stronger.

➌ What is SQL?

⬘ SQL stands for Structured Query Language.

⬗ SQL is a computer language for storing, manipulating and retrieving data stored in a relational database.

⬙ SQL has many parts

⮑ DDL
Data Definition Language
⮑ DML
Data Manipulation Language
⮑ DQL
Data Query Language
⮑ DCL
Data Control Language
⮑ TCL
Transaction Control Language

Refer 👇

https://twitter.com/swapnakpanda/status/1459504163159564294?s=20

⬖ Remember, a database is "Relational" and the language used in it is called "SQL". But it is normal to use "Relational Database" and, "SQL Database" terms interchangeably.

⬘ In a SQL Database, data are kept fully structured. Often data are very tightly coupled.

➍ What is NoSQL?

⬘ SQL Databases were good and served many purposes. But with time data volume increased like anything.

⬖ For these large volume of data, SQL was getting inefficient on many occasions. To improve the efficiency, new database designs evolved.

⬙ All these databases didn't keep it mandatory for data to be structured. Hence SQL was not going to work. So, a new term was coined "NoSQL".

✩ NoSQL doesn't mean "Not SQL" rather "Not Only SQL".

⬗ NoSQL databases are mostly of distributed architecture. Hence they follow CAP Theorem.

✩ CAP Theorem states that no distributed system can support more than any two of Consistency, Availability and Partition tolerance.

➎ Categories

Broadly databases can be categorised into

🛢
⮑ Relational
⮑ NoSQL
⮑ Document
⮑ Wide-Column
⮑ Key-Value
⮑ Graph
⮑ Time Series
⮑ Search

And, few others.

Refer 👇

https://twitter.com/swapnakpanda/status/1489856846701932546?s=20&t=gcLaQe7xn1lEfRfxLzwzdg

➏ SQL vs NoSQL

Now, as we have fundamentals cleared about both SQL and NoSQL databases, let's find out major differences.

Let's classify and then we will elaborate each one.

❍ Architecture
❍ Schema
❍ Scalability
❍ Data Structure
❍ Properties

➏.➀ Architecture

❑ SQL Databases are "Relational" while NoSQL databases are "Non-Relational".

❒ SQL Databases are not mandatorily distributed while NoSQL databases are architected for distributed systems.

➏.➁ Schema

❑ Schemas in SQL Database is mandatory and, predefined.

❒ Schemas in NoSQL Database is dynamic. It is not mandatory to define a Schema before creation of data.

➏.➂ Scalability

❑ SQL Databases are mostly "vertically scalable" means you need to increase the machine's CPU, RAM, Storage for scaling.

❒ NoSQL Databases are "horizontally scalable" means you just need to add new machines to scale up. NoSQL databases are distributed.

➏.➃ Data Structure

❑ SQL Databases are Table based.

❒ NoSQL databases are variant. There exists Document based, Key-Value based, Wide-Column Store based, Graph based and so many other types.

➏.➄ Properties

❑ SQL Databases are ACID compliant. It means consistency of data is of high priority.

❒ Where as NoSQL Databases support any 2 of CAP (Consistency, Availability and Partition Tolerance).

➐ BONUS: Which one is for you?

⬔ SQL databases are better for multi-row transactions, while NoSQL is better for unstructured data like documents or JSON.

⬕ If data can grow quickly and you want to scale up immediately on-demand, then NoSQL should be the preferred one.

⚠️ Repost Notice ⚠️

⬖ Though this is my original work, part of it was previously posted in [CHIRPBIRDICON]

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