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?

Show HN: CallFirst – blocks socials until you've made a call to someone

iFixit Teardown: iPhone 18 Pro and Pro Max

Jev 1.13 Jaggedness

TPM-Attest: Hardware-Rooted Anti-Cheat Alternative for Linux

Nimble takes some text and a schema, and makes typed decisions about the text

Show HN: Bitcoin-rs – An AI-assisted Bitcoin full node in Rust

A Dangerous Castle

Generating Artist-Like 3D Mesh Topology via Nearest-Vertex Vector Fields

I'm afraid of spiders. So I made AI look at 2k of them

Sparse resources helped my GPU-driven renderer memory usage

Gabor Fields: Orientation-Selective Level-of-Detail for Volume Rendering

OpenXLR – A Linux Variant of Elgato Wave Link

Show HN: A GeoJSON viewer that checks the bbox you declared

Thomson-1.0-Small LLM Developed by Thomson Reuters

FSD Supervised now approved in Czech Republic

WhatsApp Business Paid Support Is a Scam

NILM to recover the energy consumption of individual appliances

Show HN: Grade text from the CLI with custom rulesets and Jev

Show HN: Gleamit – dental health tracker for Android/iOS

BicDB – a PostgreSQL-compatible database for local-first apps

AlternativeTo – Crowdsourced Software Recommendations

AI Data Center Basics: What Is Linear Pluggable Optics (LPO)?

Don't Use AI to Write

DBClient: A native Mac database client for 12 engines (I'm the dev)

I found a better React color picker

The easiest-to-understand article I've read about Jev

Calibre v9.15's "Create your own adventure" writing game

Chinese CXMT to Match Micron's DRAM Manufacturing Capacity This Year

Sonnex – A DAW for macOS

The Economic Incentives Behind the Push to Pause AI