consistency
Primary-Replica Replication
Writes go to primary, then replicate asynchronously. Reads from replicas may be stale.
primary version0
writes0
synced replicas3/3
Increments version and replicates asynchronously
PRIMARY
initial_value
version 0
↓ asynchronous replication ↓
Replica-1
initial_value
v0
✓ synced
Replica-2
initial_value
v0
✓ synced
Replica-3
initial_value
v0
✓ synced
Click a replica to read from it
// replication log
No events yet
How It Works
- All writes go to designated primary node
- Primary replicates changes to replicas asynchronously
- Reads can happen from any replica
- Replica reads may be stale (eventual consistency)
Use Cases
- MySQL/PostgreSQL read replicas
- MongoDB replica sets
- Redis replication
- Read-heavy workloads with stale-read tolerance