(POC): Remove some hashmap lookups in distribution lookup

[scsmithr]

Partially addresses #56

Also removes IndexMap

Wip. The timings are down, but there might be alternative approaches here that I may try to explore.

This approach would also remove some flexibility with what we allow in a distribution, but I don't think that matter for this.

Timings

$ time cargo run --release -- -s 0.01 --output-dir=/tmp/tpchdbgen-rs-001

Tiny SF to capture the initialization time, not actual data generation.

main: 2.851s, 2.694s, 2.764s
this branch: 1.860s, 1.867s, 1.864s

[alamb]

Thanks @scsmithr -- this is looking great. Let me know when / it is ready for a review

[alamb]

👍

[alamb]

😆

[alamb]

I started going through this PR -- the idea is really nice. I will try and bash out the conversion for the remaining distributions

[scsmithr]

I started going through this PR -- the idea is really nice. I will try and bash out the conversion for the remaining distributions

Yeah my bad for the slowness here. Feel free to take it over.

My only real concern is we lose on flexibility on what distributions we can use. But that's my programmer brain talking -- in reality we only care about that one distribution file.

[alamb]

Yeah my bad for the slowness here. Feel free to take it over.

No worries -- this is a great step. I also have some ideas about how to avoid hash maps entirely. But I'll do that as a follow on PR potentially.

Right now me and copilot are going to apply your pattern to all the remaining distributions :)

My only real concern is we lose on flexibility on what distributions we can use. But that's my programmer brain talking -- in reality we only care about that one distribution file.

Yeah, I agree -- the TPCH data generator hasn't changed for at least 14 years. I don't think flexibility is particularly important