Asynchronous Database Replication Explained | WAL, Oplog & Master-Slave | System Design #9

🚀 Welcome to Episode 9 of the System Design Series! In the previous episode, we explored Synchronous Database Replication and how changes are replicated to replicas before a write is considered complete. In this video, we'll dive deep into Asynchronous Database Replication and understand how databases replicate changes from a Primary (Master) to Replica (Slave) without making the client wait for every replica. 📚 In this video, you'll learn: ✅ What is Asynchronous Database Replication? ✅ Master-Slave / Primary-Replica Architecture ✅ How Write Queries are processed ✅ How database changes are recorded in log files ✅ Write-Ahead Logs (WAL) ✅ How changes are copied from the Master to the Replica ✅ Understanding the replication flow step-by-step ✅ How MongoDB uses Oplog for replication ✅ Changed rows / operations and their corresponding log entries ✅ How the Replica reads and applies changes ✅ Eventual Consistency ✅ Advantages and trade-offs of Asynchronous Replication We'll visualize the complete flow: Client → Master → Log File → Slave/Replica and understand what happens behind the scenes when a database record is modified. 📺 Complete High-Level Design (HLD) Playlist: 🔗    • System Design | Complete High-Level Design...   📃 WAL Article: 🔗 https://www.architecture-weekly.com/p... 📃 MongoDB Oplog official documentation: 🔗 https://www.mongodb.com/docs/manual/c... 📌 Previous Videos: Episode 1 – What is System Design? Episode 2 – Scalability Episode 3 – Load Balancing Episode 4 – Build a Load Balancer using Nginx Episode 5 – Performance Testing using k6 Episode 6 – Deployment Architectures & Database Scaling Episode 7 – Database Partitioning & Sharding Episode 8 – Synchronous Database Replication 🎯 Next Video: We'll continue exploring Database Replication and understand Master-Master Architecture and Masterless Architecture. If you're preparing for System Design interviews or want to understand how databases work behind the scenes in large-scale distributed systems, this series is for you. 👍 Like 💬 Comment 🔄 Share 🔔 Subscribe For more content on System Design, Backend Development, Distributed Systems, Cloud Computing, and Software Engineering. #SystemDesign #DatabaseReplication #AsyncReplication #WAL #Oplog #MongoDB #DistributedSystems #Database #Backend #SoftwareEngineering #HLD