Distributed DatabasesdebuggingBeginner

Users see their profile revert right after saving

Symptoms

  • After saving a profile change, an immediate page refresh shows the old value.
  • A refresh a few seconds later shows the new value.
  • Started after read replicas were added.
-- app read routing:
write  → primary
read   → any replica (round-robin)

replication lag on replica B: ~800 ms

Investigate

Inspect areas in any order (0/4 inspected). When you think you know the root cause, commit to it.

Read routing
Replication lag
Caching layer
The write itself