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?

Hooked on Tuna

Rooting Multiple ISPs with Hyperglass

Brazil's Largest Port Hit by Major IT Outage; Suspected Ransomware Cyberattack

Ask HN: Why doesn't Ramp AI Index include OpenRouter or other aggregators?

Anthropic Software Engineer Salaries

The indie game community is in disarray over AI and Big Walk

State of the tech job market: late 2026

Discontinuation of Google and Apple Accounts Linking to Nintendo Accounts

Show HN: A company running in an AI harness

GSD-LQ: Zero-calibration sub-4-bit compression and 7B in 3.78 GB VRAM

Tokenizers

Toyota Sees a U.S. Future for Tiny Trucks with a Devoted Following (Kei Trucks)

Microsoft employee price list from 1987

A great old-timey game-programming hack (2013)

How to Be a Good Farrier: What the Car Teaches Us About AI and Your Job

E-means: outperforming k-means (in one-tenth the epochs)

Reddit Reviews

The Sicilian Citrus Family Tree

Vote the Page: a website rewritten every hour by its top-voted prompt

Claude usage limit reset is a gambler's rush

Could AI's leading men become as powerful as Ford or Rockefeller?

Planetocopia (2002-2017)

Show HN: HC – a HyperCard clone that runs original stacks on today's Macs

Try my daily game whosit

Claude Code is accidentally exposing secrets all over GitHub

A Schema Named Hash Sent Our Ruby SDK into Infinite Recursion

Show HN: Kotlean: write Android apps in Lean

Silent degradation is back, Fable and Mythos 5.2 perform at level of Opus 5.5

Yahoo is betting the house on its new AI, from search to all its services

Getting Started with OpenIndiana