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?

OpenCRA

The Gap Map v0.1

Show HN: Sprytools – 26 small developer APIs behind one key

Netherlands recruited 29 top scientist leaving U.S. under Trump

Hacking the bureaucracy to get stuff done (2020)

A visual calculator to estimate and compare LLM API pricing

Software is eating the world, AUTONOMOUSLY

Space Force's high-powered electro beam nullifies hostile satellites

Show HN: SigMap – deterministic repo maps for AI coding agents

Ask HN: What are alternative to Upwork for side gig?

Show HN: Sdlc factory built on pi.dev:intent->DDD->architecture->tested code

Court allows far-right leader Marine Le Pen to run for president

A design system for Rust/egui where token violations fail the build

The Perfect Cripple: A User Guide to Being Palatable

Discovery helps explain why solid-state batteries often fail

Amazon Returns to US Bond Market to Fund AI Infrastructure Build

The Popup That Says the Quiet Part Out Loud

I was wrong about Duff's device

Agents don't need smarter models, they need a map

Dua Lipa opens library for banned and censored books in Portugal

Gladia-CLI: A command-line tool for audio transcription

Effects as Capabilities

Yamanote.fun – A complete soundscape for Tokyo's Yamanote line

98% Isn't Much

A better way to tie your gym shorts. (Or any drawstring) [video]

Entering the Agentocene: A Statistical Investigation of AI-Era Coding

Why is integration so much harder than differentiation? (2020)

Best iOS Weight Lifting App for iPhone and Apple Watch (2026)

Turn commodity WiFi signals into real-time spatial intelligence

Show HN: What if your personal website was ChatGPT?