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Implement native interleave for ListView#9558

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vegarsti wants to merge 5 commits intoapache:mainfrom
vegarsti:list-view-interleave-native
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Implement native interleave for ListView#9558
vegarsti wants to merge 5 commits intoapache:mainfrom
vegarsti:list-view-interleave-native

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@vegarsti vegarsti commented Mar 15, 2026 •
edited by alamb
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This PR adds a native implementation of interleave for the ListView type. Also adds a benchmark.

Performance improves by more than 30% in all cases in the benchmark:

Benchmark Time (branch) Change vs baseline Speedup
list_view<i64>(0.1,0.1,20) 100 2.40 µs −41.2% 1.70×
list_view<i64>(0.1,0.1,20) 400 6.50 µs −36.6% 1.58×
list_view<i64>(0.1,0.1,20) 1024 15.67 µs −38.1% 1.62×
list_view<i64>(0.1,0.1,20) 1024 4-arr 15.76 µs −35.7% 1.55×
list_view<i64>(0.0,0.0,20) 100 1.49 µs −41.0% 1.70×
list_view<i64>(0.0,0.0,20) 400 3.99 µs −30.3% 1.43×
list_view<i64>(0.0,0.0,20) 1024 9.58 µs −40.7% 1.69×
list_view<i64>(0.0,0.0,20) 1024 4-arr 9.45 µs −36.2% 1.57×

@github-actions github-actions bot added the arrow Changes to the arrow crate label Mar 15, 2026
@vegarsti vegarsti force-pushed the list-view-interleave-native branch from a1131f2 to 16f2287 Compare March 15, 2026 15:42
@vegarsti vegarsti mentioned this pull request Mar 16, 2026
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brancz commented Mar 16, 2026

Do you mind comparing this to the fallthrough performance of #9562 ?

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vegarsti commented Mar 16, 2026

Do you mind comparing this to the fallthrough performance of #9562 ?

Oh for sure, thanks for reminding me!

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vegarsti commented Mar 16, 2026 •
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Updated the description with results now. It's not looking like a win..!

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brancz commented Mar 16, 2026

I would say let's merge the fallthrough and iterate on this version. I'm sure there are several possibilities for optimizations.

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asubiotto commented Mar 16, 2026

FWIW I pushed up the branch I've had marinating locally for a month or two in case it's helpful: main...polarsignals:arrow-rs:asubiotto/lvinterleave. I believe the benchmarks showed a slight regression for interleaves of small lists, but overall the perf was an improvement. I'm not able to take a closer look right now, but sharing in case it's helpful.

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vegarsti commented Mar 18, 2026

FWIW I pushed up the branch I've had marinating locally for a month or two in case it's helpful: main...polarsignals:arrow-rs:asubiotto/lvinterleave. I believe the benchmarks showed a slight regression for interleaves of small lists, but overall the perf was an improvement. I'm not able to take a closer look right now, but sharing in case it's helpful.

Thank you!

@vegarsti vegarsti force-pushed the list-view-interleave-native branch from 6e8412e to b18c3a6 Compare March 19, 2026 12:48
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vegarsti commented Mar 19, 2026

Updated implementation and results now!

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asubiotto commented Apr 15, 2026

Sorry for dropping the ball on this! I think this is going in the right direction but when I pulled this in to try it out I realized that it doesn't work very well when interleaving listviews with a high number of shraed elements (i.e. offset/size windows are overlapping). I think we can get the best of both worlds by computing a heuristic: i.e. how many values are referenced vs how many values are in the backing array to figure out if we want to do per-row copies as this pr does or just a full concat of the backing slice which preserves overlapping encodings and can be much cheaper in the end. Here is a commit that implements that on top of this PR with a benchmark: polarsignals@7cb6880

There is a slight perf hit vs your branch to compute the heuristic (summing referenced sizes), but I think it's worth it in the grand scheme of things:

interleave list_view<i64>(0.1,0.1,20) 100 [0..100, 100..230, 450..1000]
                        time:   [2.8553 µs 2.8661 µs 2.8777 µs]
                        change: [−39.782% −39.429% −39.058%] (p = 0.00 < 0.05)
interleave list_view<i64>(0.1,0.1,20) 400 [0..100, 100..230, 450..1000]
                        time:   [8.2066 µs 8.2440 µs 8.2838 µs]
                        change: [−41.803% −41.460% −41.123%] (p = 0.00 < 0.05)
interleave list_view<i64>(0.1,0.1,20) 1024 [0..100, 100..230, 450..1000]
                        time:   [22.291 µs 22.424 µs 22.580 µs]
                        change: [−39.377% −38.883% −38.328%] (p = 0.00 < 0.05)
interleave list_view<i64>(0.1,0.1,20) 1024 [0..100, 100..230, 450..1000, 0..1000]
                        time:   [21.744 µs 21.868 µs 22.003 µs]
                        change: [−40.397% −39.966% −39.515%] (p = 0.00 < 0.05)
interleave list_view<i64>(0.0,0.0,20) 100 [0..100, 100..230, 450..1000]
                        time:   [1.7642 µs 1.7770 µs 1.7937 µs]
                        change: [−36.120% −35.680% −35.219%] (p = 0.00 < 0.05)
interleave list_view<i64>(0.0,0.0,20) 400 [0..100, 100..230, 450..1000]
                        time:   [5.1748 µs 5.2052 µs 5.2392 µs]
                        change: [−29.000% −28.500% −28.000%] (p = 0.00 < 0.05)
interleave list_view<i64>(0.0,0.0,20) 1024 [0..100, 100..230, 450..1000]
                        time:   [12.528 µs 12.631 µs 12.741 µs]
                        change: [−29.293% −28.511% −27.801%] (p = 0.00 < 0.05)
interleave list_view<i64>(0.0,0.0,20) 1024 [0..100, 100..230, 450..1000, 0..1000]
                        time:   [13.009 µs 13.098 µs 13.192 µs]
                        change: [−26.841% −26.193% −25.550%] (p = 0.00 < 0.05)
interleave list_view_overlapping<i64>(80x,20) 100 [0..100, 100..230, 450..1000]
                        time:   [1.8046 µs 1.8271 µs 1.8547 µs]
                        change: [−44.472% −43.715% −42.935%] (p = 0.00 < 0.05)
interleave list_view_overlapping<i64>(80x,20) 400 [0..100, 100..230, 450..1000]
                        time:   [3.3896 µs 3.4283 µs 3.4689 µs]
                        change: [−66.387% −66.073% −65.773%] (p = 0.00 < 0.05)
interleave list_view_overlapping<i64>(80x,20) 1024 [0..100, 100..230, 450..1000]
                        time:   [5.7748 µs 5.8133 µs 5.8482 µs]
                        change: [−72.104% −71.879% −71.641%] (p = 0.00 < 0.05)
interleave list_view_overlapping<i64>(80x,20) 1024 [0..100, 100..230, 450..1000, 0..1000]
                        time:   [6.2896 µs 6.3539 µs 6.4243 µs]
                        change: [−69.684% −69.377% −69.083%] (p = 0.00 < 0.05)

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alamb commented Apr 16, 2026

Sorry for dropping the ball on this! I think this is going in the right direction but when I pulled this in to try it out I realized that it doesn't work very well when interleaving listviews with a high number of shraed elements (i.e. offset/size windows are overlapping).

Could you perhaps make a PR that adds this case as a benchmark?

alamb
alamb reviewed Apr 16, 2026
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Comment thread arrow/benches/interleave_kernels.rs
let list_i64_no_nulls =
create_primitive_list_array_with_seed::<i32, Int64Type>(8192, 0.0, 0.0, 20, 42);

let list_view_i64: ListViewArray =
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@alamb alamb Apr 16, 2026

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Can we please add this benchmark as a separate PR (to make it easier to run the automated benchmark runners)?

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@vegarsti vegarsti Apr 16, 2026

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Definitely!

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@vegarsti vegarsti Apr 16, 2026

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#9738

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@alamb alamb Apr 16, 2026

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merged!

@vegarsti vegarsti mentioned this pull request Apr 16, 2026
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alamb pushed a commit that referenced this pull request Apr 16, 2026
@vegarsti @asubiotto
Add benchmark for ListView interleave (#9738)
c5fed03 
Ref #9558 (comment)

---------

Co-authored-by: Alfonso Subiotto Marques <alfonso.subiotto@polarsignals.com>
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Add native ListView support for interleave kernel

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