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

1•LawZiL•11mo 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•11mo 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•11mo 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•11mo 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•11mo ago

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

Show HN: Global DNS record propagation visualization

Special-Use Domain 'home.arpa.' (2018)

OpenClaw Got Safer in Public

Forget Ambition: A Case for Hopeless Creativity

China Planted 78B New Trees Affecting Its Water Cycle

My local agentic dev setup today

Exclusive eBook: Inside the stealthy startup that pitched brainless human clones

Lightweight OpenCode profile for routine dev work with focused agents

I Built GeoGuesser but for Guns

Show HN: Parse your chat exports to find restaurants, trips, and activity ideas

Ubuntu / Canonical Launchpad Down

'Completely horrible': UK job hunters share frustration with AI interviews

SlothDB a 5X Faster Alternative to DuckDB, ClickHouse DB

RLS sounds great until it isn't

Languages: We must save dying tongues (2014)

Ask HN: Bedrock,Vertex AI etc. Support Anthropic Models

Rats free each other from cages (2011)

Mike Stonebraker on Disagreeing with Google, Postgres, Future Problems [video]

Norway: The Supreme Court dismisses all accusations against Jw

Claude Code Connected to Apple Car Play and Android Auto [video]

Are you richer than your neighbor?

Meta's Big Tobacco PR Tactics

The AI supply crunch is here

Barbara Liskov on Dijkstra, Abstraction, Distributed Systems [video]

U.S. Seizes $15B in Bitcoin in Crypto 'Scam' Crackdown

Monopoly Concepts in Microeconomics: De Beers and Diamond Industry

Show HN: Kencode – Compact Kotlin serialization for URLs and labels

If I Could Make My Own GitHub

Apple Says Mac Studio and Mac Mini Will Be in Short Supply for Months

A text editor as a user interface