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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– Oleksii Petrov's LinkedIn: https://www.linkedin.com/in/alexhelkar/

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!

PgBouncer at Scale: Lessons from 243 PostgreSQL DBs

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PgBouncer at Scale: Lessons from 243 PostgreSQL DBs

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