Rich-T-kid commented on PR #10094:
URL: https://github.com/apache/arrow-rs/pull/10094#issuecomment-4671511320
Yea I agree, wanted to give it an attempt. The main issue is that if the
run_ends aren't re-written the logical array that is expressed is incorrect.
For example
```
// represents: [a,a,b,b,b,a,a,a,c,c]
Runarray = {run_ends: [2,5,8,10], values:["a","b","a","c"]}
let sliced = Runarray.slice(3,5)
// represents: [b,b,a,a,a]
```
but in both arrays the run_ends are `[2,5,8,10]` and the values are
`["a","b","a","c"]`. Logical_len & logical_offset are the only differences
between the two. We also cant just naively cut up the values array, this would
cause the run_ends buffer to misrepresent the correct logical form.
I think its fine to leave as it is, the swapping values pattern is somewhat
uncommon and the performance boost should be negligible.
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