Ask HN: How can I load test PostgreSQL but avoid changing actual data?

1•LawZiL•1y ago

I'm running a load test on my Node.js application and want to simulate realistic write-heavy scenarios to stress test the system — especially the PostgreSQL database.

There's a part of the code that performs UPDATE queries, but during load testing, I don't want these updates to actually change the state of the database. However, I still want the database to experience the full impact of the update — query planning, locking, I/O, WAL writes, etc. — so I can measure how it affects performance under peak load.

Is there a best-practice approach to achieve this?

So far, the most viable option I’ve found is to wrap the UPDATE queries in a transaction and then roll it back — that way, the queries still execute, but the state doesn’t change. Is this the right way to go? Does rollback introduce any performance overhead that would skew my results? Are there better or more realistic alternatives that simulate the full write path without persisting changes?

Thanks in advance!

Comments

sargstuff•1y ago

pgbench[2] / pgreplay-go[0] / python locust[1]

very old school approach:

Misuse sql VIEW[3][4] to generate a temporary parallel table setup. Testing database separate from production database would be 'better', IMHO.

-----

[0] pgreplay-go : https://github.com/gocardless/pgreplay-go

[1] python locust : https://miguel-codes.medium.com/unconventional-load-testing-...

[2] pgbench load testing :

   a) https://medium.com/@c.ucanefe/pgbench-load-test-166bdfb5c75a

   b) https://neon.tech/blog/autoscaling-in-action-postgres-load-testing-with-pgbench

   c) https://hackernoon.com/how-to-create-and-load-test-data-in-postgresql-i41e353m

----------------------------

[3] : a) https://hashrocket.com/blog/posts/materialized-view-strategi...

      b) https://tech.jonathangardner.net/wiki/PostgreSQL/Materialized_Views

      c) https://stackoverflow.com/questions/77603705/what-is-the-use-of-materialized-view-in-postgresql

[4] : https://en.wikipedia.org/wiki/View_(SQL)

LawZiL•1y ago

but again, how can i perform the query, but not actually change the state, i really need the state to keep untouched, but be able to perform the query itself.

MatthiasPortzel•1y ago

> Does rollback introduce any performance overhead that would skew my results?

I would expect it to be the other way around—since the transactions are rolled back and not committed, they would have significantly less performance impact. But I’m working from an academic model of the database.

apothegm•1y ago

Load test against a clone instead of a DB whose contents you care about?

Rowly – a free open-source security scanner

Mayflies and the Toxic Side of "Carpe Diem"

The Evolution of Go Generics: A Retrospective from 1.18 to 1.27

Kill Switch (X-Files episode)

Colors' Package Skills Catalog is live

Ask HN: How has AI helped your personal algorithmic trading strategy?

Georgia police officers fired after Flock camera misuse

Ask HN: What would convince you that a closed source messaging app is secure?

How to Find the Most Talented People on Earth (Tyler Cowen, 2025)

Framework for Digital Media Lifespans and EOL Safe Harbors

Search Engine – MP3Juice

Reducing Graphics API Complexity: A Clean Slate Design for Modern GPUs

Edge Browser: End Date for Manifest V2 Set – End for uBlock Origin

Ship to Burn

I think I found the best way to find a baby name

Show HN: Pacific Slate: a self-hosted, model-agnostic multi-agent AI assistant

Show HN: Wardline, a Go proxy that auto-blocks compromised AI agents

Is it all just vapourware?

I've yet to see any"My AI went rogue and caused us to recognise a workers union

Romania Extends Nuclear Reactor Output by Nine Days After Danube Blasts

TubeStream – Turn a YouTube channel into a podcast you can listen to

Show HN: Form cohorts in your city for study and business

Codreo AI Mail – AI Outlook Email Assistant

Tuxedo No. 2 – Cocktail recipes

Endless Execution

New Zealand lost its music media, and what we're building to replace it

Show HN: Standards – Opinionated Linter

TV Station Launches Multiple 4K Broadcasts OTA on ATSC 1.0 (2024, video)

Ask HN: Recommended Merchant of Record and Affliate Setup

FreeBSD Storage for OpenShift with Democratic CSI