The default shared memory is 128MiB, not even 1% of typical machines today. A benchmark run with these settings is effectively crippling your hardware by making sure 99% of your available memory is ignored by postgres. It's an invalid benchmark, unless redis is similarly crippled.

"If we don't need performance, we don't need caches" feels like a great broader takeaway here.

It's crazy how wildly inaccurate "top-of-the-list" LLMs are for straightforward yet slightly nuanced inquiries.

I've asked ChatGPT to summarize Go build constraints, especially in the context of CPU microarchitectures (e.g. mapping "amd64.v2" to GOARCH=amd64 GOAMD64=v2). It repeatedly smashed its head on GORISCV64, claiming all sorts of nonsense such as v1, v2; then G, IMAFD, Zicsr; only arriving at rva20u64 et al under hand-holding. Similar nonsense for GOARM64 and GOWASM. It was all right there in e.g. the docs for [cmd/go].

This is the future of computer engineering. Brace yourselves.

> copy pasting some configuration I might not really understand

Uh, yea... why would you? Do you do that for configurations you found that weren't from LLMs? I didn't think so.

I see takes like this all the time and I'm really just mind-boggled by it.

There are more than just the "prompt it and use what it gives me" use cases with the LLMs. You don't have to be that rigid. They're incredible learning and teaching tools. I'd argue that the single best use case for these things is as a research and learning tool for those who are curious.

Quite often I will query Claude about things I don't know and it will tell me things. Then I will dig deeper into those things myself. Then I will query further. Then I will ask it details where I'm curious. I won't blindly follow or trust it like I wouldn't a professor or anyone or any thing else, for that matter. Just like I would when querying a human for or the internet in general for information, I'll verify.

You don't have to trust it's code, or it's configurations. But you can sure learn a lot from them, particularly when you know how to ask the right questions. Which, hold onto your chairs, only takes some experience and language skills.

So run the LLM in an agent loop: give it a benchmarking tool, let it edit the configuration and tell it to tweak the settings and measure and see how much if a performance improvement it can get.

That's what you'd do by hand if you were optimizing, so save some time and point Claude Code or Codex CLI or GitHub Copilot at it and see what happens.

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IME very very few people tune the underlying host. Orgs like uber, google or whatever do but outside of that few people know what they're really doing/cares that much. Easier to "increase EC2 size" or whatever.

Defaults have all sorts of assumptions built into them. So if you compare different programs with their respective defaults, you are actually comparing the assumptions that the developers of those programs have in mind.

For example, if you keep adding data to a Redis server under default config, it will eat up all of your RAM and suddenly stop working. Postgres won't do the same, because its default buffer size is quite small by modern standards. It will happily accept INSERTs until you run out of disk, albeit more slowly as your index size grows.

The two programs behave differently because Redis was conceived as an in-memory database with optional persistence, whereas Postgres puts persistence first. When you use either of them with their default config, you are trusting that the developers' assumptions will match your expectations. If not, you're in for a nasty surprise.

> If you judge Postgres without tuning it - that's not Postgres being slow, that's the developer being naive.

Didn't OP end by picking Postgres anyway?

It's the right answer even for a naive developer, perhaps even more so for a naive one.

At the end of the post it even says

>> Having an interface for your cache so you can easily switch out the underlying store is definitely something I’ll keep doing

He concluded postgresql to be fast enough, so what's the problem?

IOW, he judged it fast enough.

I've not tried it myself but I believe that's what pgtune does: https://github.com/gregs1104/pgtune