Three-AZ Order Path: Stateless Rows, Fenced State

Three-AZ Order Path: Stateless Rows, Fenced State An architecture diagram generated by Archify. Client · order writes, peak 231/s · Architecture component Client order writes, peak 231/s Load Balancer · health-checks every instance · Architecture component Load Balancer health-checks every instance API in AZ-a · stateless, no session state · AZ-a failure domain: everything inside dies together · drained if AZ-a dies API in AZ-a stateless, no session state drained if AZ-a dies API in AZ-b · stateless, no session state · AZ-b failure domain: everything inside dies together · main serving row API in AZ-b stateless, no session state main serving row API in AZ-c · stateless, no session state · AZ-c failure domain: everything inside dies together · drained if AZ-c dies API in AZ-c stateless, no session state drained if AZ-c dies DB Primary · sync standby ACKs writes · State failure domain: fencing and RPO/RTO live here · crown: exactly one writer DB Primary sync standby ACKs writes crown: exactly one writer DB Sync Standby · promotes on failover · State failure domain: fencing and RPO/RTO live here · epoch 8 after promote DB Sync Standby promotes on failover epoch 8 after promote Replicated Queue · 3 consumers, checkpointed · State failure domain: fencing and RPO/RTO live here · poison to dead-letter Replicated Queue 3 consumers, checkpointed poison to dead-letter Backup Store · snapshot plus WAL · State failure domain: fencing and RPO/RTO live here · RPO 1 min, RTO 5 min Backup Store snapshot plus WAL RPO 1 min, RTO 5 min order writes at peak healthy instance route spillover route spillover route write, standby ACKs sync copy, epoch fence outbox events per order snapshot plus WAL AZ-a failure domain: everything inside dies together AZ-b failure domain: everything inside dies together AZ-c failure domain: everything inside dies together State failure domain: fencing and RPO/RTO live here Legend Backend Database Cloud Message bus External