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Improve validate_utf8 performance #2048

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merged 6 commits into from
Jul 26, 2022
Merged

Improve validate_utf8 performance #2048

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1fb1222
added utf8 validation bench
tfeda Jul 12, 2022
2f30720
improve utf8 validation performance
tfeda Jul 12, 2022
e52c4e3
fix bench clippy errors
tfeda Jul 12, 2022
e173f46
Merge branch 'master' of https://github.com/apache/arrow-rs
tfeda Jul 14, 2022
f57389d
Merge branch 'master' of https://github.com/apache/arrow-rs
tfeda Jul 19, 2022
17678fa
Add is_char_boundary() to utf8 validation
tfeda Jul 19, 2022
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15 changes: 13 additions & 2 deletions arrow/benches/array_data_validate.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -37,11 +37,22 @@ fn create_binary_array_data(length: i32) -> ArrayData {
.unwrap()
}

fn array_slice_benchmark(c: &mut Criterion) {
fn validate_utf8_array(arr: &StringArray) {
arr.data().validate_values().unwrap();
}

fn validate_benchmark(c: &mut Criterion) {
//Binary Array
c.bench_function("validate_binary_array_data 20000", |b| {
b.iter(|| create_binary_array_data(20000))
});

//Utf8 Array
let str_arr = StringArray::from(vec!["test"; 20000]);
c.bench_function("validate_utf8_array_data 20000", |b| {
b.iter(|| validate_utf8_array(&str_arr))
});
}

criterion_group!(benches, array_slice_benchmark);
criterion_group!(benches, validate_benchmark);
criterion_main!(benches);
41 changes: 31 additions & 10 deletions arrow/src/array/data.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1125,16 +1125,37 @@ impl ArrayData {
T: ArrowNativeType + TryInto<usize> + num::Num + std::fmt::Display,
{
let values_buffer = &self.buffers[1].as_slice();

self.validate_each_offset::<T, _>(values_buffer.len(), |string_index, range| {
std::str::from_utf8(&values_buffer[range.clone()]).map_err(|e| {
ArrowError::InvalidArgumentError(format!(
"Invalid UTF8 sequence at string index {} ({:?}): {}",
string_index, range, e
))
})?;
Ok(())
})
if let Ok(values_str) = std::str::from_utf8(values_buffer) {
// Validate Offsets are correct
self.validate_each_offset::<T, _>(
values_buffer.len(),
|string_index, range| {
if !values_str.is_char_boundary(range.start)
|| !values_str.is_char_boundary(range.end)
Comment on lines +1133 to +1134
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@tustvold tustvold Jul 23, 2022 •
edited
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I think you can remove values_str.is_char_boundary(range.end), as the end offset is the start offset of the next string slice and will therefore be checked by that. We do not need to check the final offset as if the end of the string is not a valid char boundary, the string as a whole would fail validation.

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I realized an additional subtlety with this, if the offsets buffer is sliced, you need to validate that this slicing is at a valid boundary, which a naive implementation of the above might miss.

Theoretically you only need to validate the range of values covered by the offsets, which might be another possible optimisation 🤔

{
return Err(ArrowError::InvalidArgumentError(format!(
"incomplete utf-8 byte sequence from index {}",
string_index
)));
}
Ok(())
},
)
} else {
// find specific offset that failed utf8 validation
self.validate_each_offset::<T, _>(
values_buffer.len(),
|string_index, range| {
std::str::from_utf8(&values_buffer[range.clone()]).map_err(|e| {
ArrowError::InvalidArgumentError(format!(
"Invalid UTF8 sequence at string index {} ({:?}): {}",
string_index, range, e
))
})?;
Ok(())
},
)
}
}

/// Ensures that all offsets in `buffers[0]` into `buffers[1]` are
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