My LSM tree was slower than a B-tree. Then I profiled it

Re:My LSM tree was slower than a B-tree. Then I profiled it by shermantanktop on Thursday June 18, 2026 @04:06PM (#48590802)

I'm called in to consult on a performance problem on a scaled service. Team was load testing their code and seeing low throughput:

Me: so you have an in-memory cache, right?

Them: yes!

Me: what is the TTL?

Them: Oh, it's not set, oops. Here, let's set it to 1 minute. Hey look, the performance went way up!

Me: okay, great. When you say 1 minute, do you mean 60 seconds?

Them: uh...wait...uh....oh, the unit is seconds. Wait, why is the performance so good with a 1 second TTL?

Me: What's your load test?

Them: We crank 1M TPS fetching the same 30 items over and over.

Me: ....

I totally agree about the power of profiling but profiling without understanding would not have helped this team.

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Re:My LSM tree was slower than a B-tree. Then I profiled it by FarmerPotato on Thursday June 18, 2026 @04:12PM (#48590872)

So the author is doing a self-learning exercise about profiling pre-production code, and you're disagreeing with them by comparing it to a commercial contract. I'm sure you've never, ever made a dumb mistake while getting paid.

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Re:My LSM tree was slower than a B-tree. Then I profiled it by shermantanktop on Thursday June 18, 2026 @05:17PM (#48591746)

I've even made dumb mistakes while NOT getting paid. But even so, I have no idea what you're talking about.

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