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?

Nvidia board urged to consider 'return of Jensen Huang' by two major investors

GCVE is a fresh, open approach to vulnerability identification and numbering

Fixing a WebKit bug to see if promises are made of train tracks

AI School Bus Cameras Cash in on Drivers Who Fail to Stop

Show HN: AI Time Estimator – how long Claude Code will take, from your own logs

Part Time Monkey

AI Company Employees Should Unionize

Where We'll Live in the Future

The Ontological Divergence of Artificial Intelligence

A 27-byte telemetry response nobody reads freezes Claude Desktop every two days

An open letter to the Nvidia Board of Directors

A simple website to test if your bot is detectable

Big Tech's Left Turn

Lirz Ads

Taboos and Self-Censorship Among U.S. Psychology Professors (2025)

Show HN: Flipbook Foundry – animated stick figures baked into a font

Show HN: Blaris – Windowless Random-Access LZSS for Constrained Microcontrollers

PinNote – Pin notes to your iPhone Lock Screen

Show HN: Coppice – A local desktop app for multi-agent coding

Ask HN: Is there a way to use Gemini API Keys with Antigravity?

Jensen's Been Moving Lately

Show HN: In-browser object removal, 1s on WebGPU, photo never leaves your device

Show HN: Model-share – see which Claude models used your weekly limit

Show HN: Chopper, a tiny edge model that keeps only useful text in 50 ms

Nonna's ragù: AI skill files only get you started

Caruana Hits 2800, Within 7.2 Points of Carlsen's World No. 1 Spot

The VHDL standard's float package gets sqrt(2) wrong

Christophe Pettus: Stop Using AI to Report PostgreSQL Bugs

LLMs as Consensus Machines

Polo: A Wayland Mate Compositor