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Allow specialized implementations to produce hints for the array adapter #3765

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Merged
merged 1 commit into from
Oct 11, 2022
Merged

Allow specialized implementations to produce hints for the array adapter #3765

merged 1 commit into from
Oct 11, 2022

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@isidentical
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@isidentical isidentical commented Oct 7, 2022 •
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Which issue does this PR close?

Closes #3762.

Rationale for this change

More details on #3762, but simply this allows us to instruct array/scalar function adapter to skip padding some arguments since the specialized version of functions don't need them.

What changes are included in this PR?

A new make_scalar_function_with_hints API (not public) that can take a list of hints and then map them to corresponding arguments and use it to decide whether they need padding or not.

This PR also provides usage of the new hints API, which in turn can speed-up regex_replace up to 1.3x.

Are there any user-facing changes?

No, this is a new API / optimization that can provide up to %25 speed-up.

@github-actions github-actions bot added the physical-expr Changes to the physical-expr crates label Oct 7, 2022
@isidentical isidentical marked this pull request as ready for review October 7, 2022 22:48
alamb
alamb approved these changes Oct 11, 2022
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Makes sense to me -- thank you @isidentical

I wonder if you have any benchmark results that show this pattern improving performance?

datafusion/physical-expr/src/functions.rs
/// - (default) `false`: indicates the argument needs to be padded if it is scalar
/// - `true`: indicates the argument can be converted to an array of length 1
///
pub(crate) fn make_scalar_function_with_hints<F>(
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The fact that this is pub(crate) is good given its specialized nature (and potential possibility of change)

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isidentical commented Oct 11, 2022

I wonder if you have any benchmark results that show this pattern improving performance?

Yep, I was playing with the idea of using the existing null buffers for regex_replace when I noticed that almost ~30% of the time was spent on here (if the input is a sparse-ish array). The example here isidentical#3 shows about ~%20-25 speed-up, and if we go and make it even more sparse the speed-up factor can increase up to %30-%35 (since there isn't much regex processing, all the time was spent on padding arrays with data we won't be using at all).

Also a subsequent optimization (using the existing null buffers) was unnoticeable before this change, but now we can clearly see the benefit of it since the actual time is now spent on result array construction inside regex_replace (instead of array padding on the scalar adapter).

@isidentical isidentical force-pushed the gh-3762 branch 2 times, most recently from 1e858c5 to aa9667a Compare October 11, 2022 16:24
@isidentical isidentical requested a review from alamb October 11, 2022 16:25
alamb
alamb approved these changes Oct 11, 2022
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Looks great @isidentical !

datafusion/physical-expr/src/regex_expressions.rs
(_, true, true, true) => Ok(make_scalar_function_with_hints(
_regexp_replace_static_pattern_replace::<T>,
vec![
Hint::Pad,
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😍

@alamb alamb merged commit f132259 into apache:master Oct 11, 2022
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alamb commented Oct 11, 2022

Thanks again @isidentical

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ursabot commented Oct 11, 2022

Benchmark runs are scheduled for baseline = 8db6af2 and contender = f132259. f132259 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ec2-t3-xlarge-us-east-2] ec2-t3-xlarge-us-east-2
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on test-mac-arm] test-mac-arm
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-i9-9960x] ursa-i9-9960x
[Skipped ⚠️ Benchmarking of arrow-datafusion-commits is not supported on ursa-thinkcentre-m75q] ursa-thinkcentre-m75q
Buildkite builds:
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java

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Allow specialized physical functions to provide hints for the array adapter

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