Mastering ACID
Transactions
Explore Atomicity, Consistency, Isolation, and Durability through interactive animations and real-world scenarios.
The ACID Properties
Click each card to explore interactive demonstrations.
Atomicity
All operations complete successfully, or none do. It’s “all or nothing.”
Consistency
Transactions bring the database from one valid state to another.
Isolation
Concurrent transactions don’t interfere with each other.
Durability
Once committed, data survives permanently, even after system failure.
Atomicity
Atomicity ensures that a transaction is treated as a single, indivisible unit of work. Either all operations within the transaction are completed successfully, or none of them are.
All operations succeed → Transaction commits
Any operation fails → Entire transaction rolls back
Bank Transfer Demo
Data Validation Rules
- Age must be > 0 and < 150
- Balance must be ≥ 0
- Email must contain @
Consistency
Consistency ensures that a transaction can only bring the database from one valid state to another. All data must satisfy all defined rules and constraints before and after the transaction.
Foreign keys, check constraints, and triggers maintain data integrity
Account balances, inventory counts, and derived values remain accurate
Isolation
Isolation ensures that concurrently executing transactions do not interfere with each other. The results are the same as if transactions were executed sequentially.
A Transaction A
RunningB Transaction B
WaitingCan read uncommitted data (dirty reads)
Only reads committed data
Same query returns same results
Complete isolation, sequential execution
Durability
Durability guarantees that once a transaction has been committed, it will remain committed even in the event of a system failure (power outage, crash, etc.). Data is written to persistent storage.
Changes are written to log before applying to database
Hardware protection for pending writes
Multiple copies across different nodes
Durability Mechanism
Real-World Use Cases
Click to see how ACID transactions protect critical business operations.
Banking & Finance
Wire transfers, account updates, and trading operations require absolute consistency.
E-commerce Orders
Inventory management and order processing must handle concurrent purchases safely.
Healthcare Records
Patient data updates require complete accuracy and audit trails for compliance.
ACID vs Non-ACID
Understanding the trade-offs between relational and non-relational approaches.
| Scenario | ACID Compliant | Non-ACID (Eventual Consistency) |
|---|---|---|
| Bank Transfer | Both accounts update together or not at all | Risk of double-spending or lost money |
| Inventory Management | Exact stock count, no overselling | Overselling possible during high traffic |
| System Crash | Automatic recovery to consistent state | Potential data corruption or loss |
| Concurrent Access | Isolated transactions, no interference | Read/write conflicts possible |
