The document explains the ACID properties of databases, which are essential for ensuring reliable transaction processing. These properties include atomicity (all-or-nothing rule), consistency (data integrity), isolation (independent transactions), and durability (persistent effects post-commit). Real-world examples illustrate each property, particularly in the context of bank transactions.

1. ACID Properties of Databases
Atomicity, Consistency, Isolation,
Durability
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2. Agenda
• 1. Introduction to ACID Properties
• 2. Atomicity
• 3. Consistency
• 4. Isolation
• 5. Durability
• 6. Real-world Examples

3. Introduction to ACID Properties
• ACID properties ensure reliable processing of
transactions in a database system.
• - A: Atomicity (All or nothing rule)
• - C: Consistency (Data integrity)
• - I: Isolation (Concurrent transactions)
• - D: Durability (Permanent effect after
transaction commit)

4. Atomicity
• Atomicity ensures that a transaction is all-or-
nothing. Either every operation within the
transaction is executed, or none are.
• Example: Bank Transfer
• - Transfer ₹1000 from Account A to Account B.
• - Subtract ₹1000 from Account A.
• - Add ₹1000 to Account B.

5. Consistency
• Consistency ensures that a transaction brings
the database from one valid state to another,
maintaining data integrity.
• Example: Bank Balance
• - Before a transfer, total funds across all
accounts should be the same before and after
the transaction.
• - Constraints like "Balance cannot be negative"

6. Isolation
• Isolation ensures that multiple concurrent
transactions occur independently without
interference.
• Example: Two transfers
• - If two people are transferring money at the
same time, their transactions should not affect
each other. Each transaction is isolated from
others.

7. Durability
• Durability ensures that once a transaction is
committed, its result will persist even in the
event of a system failure.
• Example: Power Outage
• - After successfully transferring ₹1000 from
Account A to B, even if the system crashes or
loses power, the transfer should still be
reflected in the database when it restarts.

8. Real-world Example: Bank
Transaction
• Consider transferring ₹1000 from Account A to
Account B:
• 1. **Atomicity**: Either ₹1000 is debited from
A and credited to B, or neither happens.
• 2. **Consistency**: Total balance across both
accounts should remain the same before and
after.
• 3. **Isolation**: Other transactions should

9. Summary of ACID Properties
• - **Atomicity**: Complete all steps or none.
• - **Consistency**: Maintain data integrity.
• - **Isolation**: Transactions run
independently.
• - **Durability**: Changes persist permanently.
• These properties are essential for ensuring
reliable and predictable database