# ACID & BASE Properties

## **ACID Properties (SQL Databases)**

ACID ensures **data reliability and consistency** in relational databases by enforcing strict transactional integrity.

* **Atomicity** → Transactions are **all-or-nothing** (e.g., a bank transfer completes fully or not at all).
* **Consistency** → Data **always remains valid** according to predefined rules (e.g., referential integrity).
* **Isolation** → Transactions **run independently** to prevent conflicts (e.g., locking mechanisms).
* **Durability** → Once committed, data is **permanently saved** even after failures (e.g., disk persistence).

**Best For:** Banking, finance, healthcare, stock trading.

## **BASE Properties (NoSQL Databases)**

BASE **prioritizes availability and scalability** over strict consistency, making it ideal for distributed systems.

* **Basically Available** → System **remains operational** despite failures (e.g., partial data availability).
* **Soft State** → Data **may change** over time due to background replication.
* **Eventually Consistent** → Data **syncs across nodes** but not instantly (e.g., DNS updates, social media posts).

**Best For:** Social media, e-commerce, IoT, big data analytics.

## **Comparison**

<table data-full-width="true"><thead><tr><th>Feature</th><th>ACID (SQL)</th><th>BASE (NoSQL)</th></tr></thead><tbody><tr><td><strong>Consistency</strong></td><td>Strong (Immediate)</td><td>Weak (Eventual)</td></tr><tr><td><strong>Availability</strong></td><td>Lower</td><td>Higher</td></tr><tr><td><strong>Scalability</strong></td><td>Limited</td><td>Highly Scalable</td></tr><tr><td><strong>Use Case</strong></td><td>Critical transactions</td><td>High-speed, distributed systems</td></tr></tbody></table>