Overview
This lecture explains the concept of database transactions, their importance in maintaining data consistency, and the ACID properties that transactions must follow.
Introduction to Transactions
- A database transaction is a sequence of operations treated as a single unit of work.
- All steps in a transaction must succeed together; if any step fails, all changes are reverted.
- Transactions ensure data integrity, especially when performing multiple related database operations.
Practical Examples of Transactions
- Filling fuel in a car involves steps that must be completed together for safety, illustrating the transaction concept.
- User registration apps insert login info into a user table and other info into a user info table; both inserts must succeed together.
- E-commerce purchases: order creation, stock update, and cart deletion must occur as a single transaction.
- Bank transfers: deducting money from one account and crediting another must both succeed or fail together.
ACID Properties of Transactions
- Transactions must follow ACID properties to ensure reliability and integrity in databases.
Key Terms & Definitions
- Transaction — A sequence of database operations performed as a single logical unit.
- ACID — Four properties that guarantee reliable transaction processing:
- Atomicity — Ensures all operations in a transaction succeed or none do.
- Consistency — Maintains database validity by enforcing all rules and constraints.
- Isolation — Prevents concurrent transactions from interfering with each other.
- Durability — Guarantees that once a transaction is committed, changes are permanent.
Action Items / Next Steps
- Review examples of transactions in database applications.
- Understand and remember the definitions of the ACID properties.