Guarantees for data reliability
Day 123 of 149
👉 Full deep-dive with code examples
The Bank Transfer Analogy
Transferring money from Account A to B:
- Subtract the amount from A
- Add the amount to B
What if the power goes out between steps?
- A lost $100
- B didn't get it
- Money vanished!
ACID properties are the goals that help prevent this kind of disaster.
What ACID Stands For
A - Atomicity:
"All or nothing"
- Either both steps happen, or neither
- No partial transfers
C - Consistency:
"Rules are enforced"
- Balance can't go negative
- Constraints/invariants stay true (according to your schema and business rules)
I - Isolation:
"Transactions don't see each other's incomplete work"
- Your transfer doesn't mess up someone else's
- Like each transaction runs without being confused by half-finished changes (exact guarantees depend on the isolation level)
D - Durability:
"Once done, it stays done"
- Power outage after? Data is still saved
- Written to permanent storage
Why It Matters
Without ACID:
- Money disappears or duplicates
- Inventory goes negative
- Orders get lost
- Users see incorrect data
With ACID:
- Transactions are more reliable
- Data stays consistent
- You can trust your database
A Quick Example
Transfer money from A to B:
Start transaction
Check: A has enough money ✓
Subtract amount from A
Add amount to B
Commit transaction (all done, saved!)
If anything fails → Rollback (nothing changes)
In One Sentence
ACID properties describe the guarantees a database tries to provide for transactions so changes are applied safely (or rolled back) even when things fail.
🔗 Enjoying these? Follow for daily ELI5 explanations!
Making complex tech concepts simple, one day at a time.
