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A comment on The Billion Row Challenge (1BRC) – Step-by-Step from 71s to 1.7s. Parent comment

Re:The Billion Row Challenge (1BRC) – Step-by-Step from 71s ... by scottlamb on Thursday February 22, 2024 @04:55PM (#39473845)
> For the very specific dataset used in the challenge, the hash function could be radically simplified, to just a single multiply and rotate left.

That's just a custom hash function, though; couldn't you do that with the standard std::collections::HashMap?

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Re:The Billion Row Challenge (1BRC) – Step-by-Step from 71s ... by haxen on Thursday February 22, 2024 @05:29PM (#39474220)
I didn't bother to try, so not sure. There would probably be some challenges and I don't see how I'd accomplish it without some branch instruction in the custom hasher.
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