This story shows how we strive to fix issues reported by our customers regarding inconsistent listing views on our e-commerce platform. We will use a top-down manner to guide you through our story. At the beginning, we highlight the challenges faced by our customers, followed by presenting basic information on how views are personalized on our web application. We then delve deeper into our internal architecture, aiming to clarify how it supports High Availability (HA) by using two data centers. Finally, we advertise a little Couchbase, distributed NoSQL database, and explain why it is an excellent storage solution for such an architecture.

This article is a form of a public postmortem in which we would like to share our bumpy way of revealing the cause of a mysterious performance problem. Besides unveiling part of our technical stack based on open-source solutions, we also show how some false assumptions made such a bug triage process much harder. Besides all NOT TO DOs, you can find some exciting information about performance hunting and reproducing performance issues on a small scale. As a perk, we prepared a repository where you can reproduce the problem and make yourself familiar with tools that allowed us to confirm the cause. The last part (lessons learned) is the most valuable if you prefer to learn from the mistakes of others.