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

1•LawZiL•8mo 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•8mo 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•8mo 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•8mo 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•8mo ago

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

Trump's $6T crypto plot [video]

Summary of CVE-2026-23864

Show HN: Externalized Properties, a modern Java configuration library

Collatz High Cycles Do Not Exist (K. Knight), Discrete Mathematics 349(3), 2023

Show HN: GetClawdbot – A Community Guide and Skill Hub for Clawdbot

Chanfana: OpenAPI 3.1 and Zod for Hono/itty-router on Cloudflare Workers

Syncthing: Open-Source Continuous File Synchronization

Nixtamal: Fulfilling, Pure Input Pinning for Nix

Microsoft ordered to stop tracking school children

Ask HN: What's your wiring pattern for large addressable LED installs?

The state of Linux music players in 2026

Disabling GitHub MCP on CC extended my sessions ~10%

EU-India Free Trade,Investment Protection and Geographical Indications Agreement

DeepSeek-OCR 2

From Hours to Seconds: Automating Python Security with AI?

How do you use LLMs to verify databases with minimal hallucinations?

Windows Central Eliminates Most of Its Gaming Journalists

Anthropic launches the MCP Apps open spec, in Claude.ai

Ask HN: What Happened to Apple App Clips?

You gotta think outside the hypercube

GiganticWebsites is AI and humans at its worst

Let's Talk About Those Watches in 'Severance'

How to get your first customers[for Devs]

LLM Ad Blockers are coming

Roots is a game server daemon that manages Docker containers for game servers

Russia using Interpol's wanted list to target critics abroad, leak reveals

An ultra-high-resolution map of (dark) matter

Show HN: See how much things cost in terms of your runway

Hidden Preference to Auto-Resize Columns in the Finder on macOS

Strong vs. swole: the surprising truth about building muscle