Welcome to the second episode of Architecture Deep Dive with Oleksii Petrov!

In today’s podcast, our guest — Vitaliy Kharytonskiy, Solution Architect, Prom.ua.

n this episode, Vitaliу from Prom.ua dives deep into the architecture behind one of Ukraine’s largest e-commerce platforms. He shares insights on managing 243 PostgreSQL databases, why they chose self-hosted infrastructure, and how they scale with PgBouncer. Tune in for a detailed look at connection pooling, Kubernetes, and production lessons learned.

Link to Vitalii’s presentation: "Spin-up pgbouncer for fun and profit" 🔗 https://fwdays.com/en/event/devops-fwdays-2025/review/spin-up-pgbouncer-for-fun-and-profit

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Timestamps:

00:00 - Intro

01:14 - Vitalii’s role at Prom.ua and introduction to Prom.ua platform

04:00 - What's the scale of prom.ua? How many databases do you have?

05:48 - Why did you choose self-hosted infrastructure over cloud?

08:19 - What's your typical PostgreSQL deployment configuration?

09:35 - What's the driver for having 243 PostgreSQL Databases? Is it Microservices/SOA concerns?

11:11 - Is it possible to run such an infrastructure without PgBouncer?

12:48 - Why do we need a database proxy and what's PostgreSQL's connection model?

17:54 - What are the three pooling modes of PgBouncer?

19:40 - Do we have any limitations in Transaction Pool Mode?

21:35 - Why not just use application-level pooling?

24:15 - How do you prevent PgBouncer connection starvation across services?

25:27 - Do you use PgBouncer's built-in authentication and why?

26:09 - What are the trade-offs of PGBouncer being single-threaded?

27:17 - Architecture evolution journey from Basic to Kubernetes

29:44 - Walkthough the current PostgresSQL and PGBouncer architecture at Prom.ua.

33:15 - Did you consider using PgBouncer as both an app-level and reverse proxy to the database?

34:08 - How do you structure your PgBouncer pod when using sidecar containers?

39:09 - What is the health check strategy for PgBouncer?

40:38 - What’s the best way to work with the clients_waiting metric in PgBouncer?

42:12 - Do you have autoscaling setup for PgBouncer?

43:05 - What are the key metrics to monitor for PgBouncer?

44:36 - Why use a custom DNS layer instead of relying on cloud DNS?

47:35 - Is built-in health checks implementation planned in PgBouncer?

48:30 - Do you see any development or evolution in the PgBouncer project?

49:12 - What PgBouncer log do you parse and why?

50:20 - How do you debug issues with PgBouncer?

51:23 - Can you share any stories about production incidents with PgBouncer?

52:08 - How do you handle PgBouncer Config Reloads Without Restarts?

52:45 - Final Thoughts & Advice from Vitaliy

53:57 - Don’t forget to subscribe and like!