Single Leader Replication

It is easy to understand. One node becomes a leader and gets all write actions, then sends the updated data to followers. We can read data from the follower

Multi-leader replication

There is also a way to make multiple leaders and assign followers to them. Ex: For each region, we have leaders and followers

Multi-leader topology:

1. Circular topology - A updates B, B updates C, C updates D, etc.

   ✅ Benefits

   • Fewer connections → simplest topology to configure
   • Scales better than all-to-all

   ❌ Downsides

   • Slowest convergence: updates travel one hop at a time
   • A single break in the circle disrupts the flow
   • Conflicts propagate slowly → harder to detect

2. Star topology - In a Star Topology, there is one central node that connects to all other nodes, and the peripheral nodes connect only to that central one, not to each other.

🔄 How replication works

• If B gets a write, it sends it to A
• A forwards it to C, D, E
• If D gets a write, the path is: D → A → others

There is no direct B → C replication.

c. All-to-All Topology - Every leader replicates directly to every other leader. Most commonly used one