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Cover image for System Design 12 - Data Consistency: Making Sure Your Data Agrees Everywhere
Sarva Bharan
Sarva Bharan

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System Design 12 - Data Consistency: Making Sure Your Data Agrees Everywhere

Intro:

Data consistency ensures that all parts of your system reflect the same information at the same time. It’s crucial for accurate transactions, reliable user experience, and overall system integrity in distributed systems.


1. What’s Data Consistency? Ensuring One Truth Across the System

  • Purpose: Keeps data synchronized and prevents mismatches across multiple sources or replicas.
  • Analogy: Like syncing up all clocks in a building so everyone sees the same time—no one gets left behind!

2. Types of Consistency

  • Strong Consistency: All reads reflect the latest write.
    • Example: Banking transactions—users should see updated balances immediately.
  • Eventual Consistency: Over time, all nodes become consistent, though not instantly.
    • Example: Social media feeds—posts may appear slightly delayed but will eventually align. Good read: 3 types
  • Causal Consistency: Ensures that related operations (like a comment after a post) occur in the correct order.

3. Benefits of Data Consistency

  • Reliable Data: Users get accurate, up-to-date information.
  • Prevents Anomalies: Reduces issues like double billing, inventory mismatches, and order errors.
  • Improves User Trust: Users know that the system won’t show outdated or incorrect info.

4. Real-World Use Cases

  • E-Commerce: Inventory levels should remain consistent across locations.
  • Banking: Account balances and transaction history must be immediately updated.
  • Collaborative Editing: Documents reflect real-time updates for all users.

5. Challenges and Pitfalls

  • Performance Overhead: Achieving strong consistency can impact speed.
  • Network Delays: Geographic distances can slow down synchronization.
  • Trade-Offs with Availability: Consistency often requires balancing against availability, especially in distributed systems.

Closing Tip: Data consistency is like a truth serum for your system—it ensures every part stays honest and aligned. The type you choose depends on how critical real-time accuracy is for your use case.

Cheers🥂

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