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Speedup character_length #15931

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Merged
merged 2 commits into from
May 3, 2025
Merged

Speedup character_length #15931

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3ee71fe
Character length
Dandandan May 2, 2025
2a789fb
Merge branch 'main' into speedup_character_length
Dandandan May 3, 2025
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78 changes: 48 additions & 30 deletions datafusion/functions/src/unicode/character_length.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,7 @@

use crate::utils::{make_scalar_function, utf8_to_int_type};
use arrow::array::{
Array, ArrayRef, ArrowPrimitiveType, AsArray, OffsetSizeTrait, PrimitiveBuilder,
Array, ArrayRef, ArrowPrimitiveType, AsArray, OffsetSizeTrait, PrimitiveArray,
StringArrayType,
};
use arrow::datatypes::{ArrowNativeType, DataType, Int32Type, Int64Type};
Expand Down Expand Up @@ -131,46 +131,64 @@ where
T::Native: OffsetSizeTrait,
V: StringArrayType<'a>,
{
let mut builder = PrimitiveBuilder::<T>::with_capacity(array.len());

// String characters are variable length encoded in UTF-8, counting the
// number of chars requires expensive decoding, however checking if the
// string is ASCII only is relatively cheap.
// If strings are ASCII only, count bytes instead.
let is_array_ascii_only = array.is_ascii();
if array.null_count() == 0 {
let array = if array.null_count() == 0 {
if is_array_ascii_only {
for i in 0..array.len() {
let value = array.value(i);
builder.append_value(T::Native::usize_as(value.len()));
}
let values: Vec<_> = (0..array.len())
.map(|i| {
let value = array.value(i);
T::Native::usize_as(value.len())
})
.collect();
PrimitiveArray::<T>::new(values.into(), None)
} else {
for i in 0..array.len() {
let value = array.value(i);
builder.append_value(T::Native::usize_as(value.chars().count()));
}
let values: Vec<_> = (0..array.len())
.map(|i| {
let value = array.value(i);
if value.is_ascii() {
T::Native::usize_as(value.len())
} else {
T::Native::usize_as(value.chars().count())
}
})
.collect();
PrimitiveArray::<T>::new(values.into(), None)
}
} else if is_array_ascii_only {
for i in 0..array.len() {
if array.is_null(i) {
builder.append_null();
} else {
let value = array.value(i);
builder.append_value(T::Native::usize_as(value.len()));
}
}
let values: Vec<_> = (0..array.len())
.map(|i| {
if array.is_null(i) {
T::default_value()
} else {
let value = array.value(i);
T::Native::usize_as(value.len())
}
})
.collect();
PrimitiveArray::<T>::new(values.into(), array.nulls().cloned())
} else {
for i in 0..array.len() {
if array.is_null(i) {
builder.append_null();
} else {
let value = array.value(i);
builder.append_value(T::Native::usize_as(value.chars().count()));
}
}
}
let values: Vec<_> = (0..array.len())
.map(|i| {
if array.is_null(i) {
T::default_value()
} else {
let value = array.value(i);
if value.is_ascii() {
T::Native::usize_as(value.len())
} else {
T::Native::usize_as(value.chars().count())
}
}
})
.collect();
PrimitiveArray::<T>::new(values.into(), array.nulls().cloned())
};

Ok(Arc::new(builder.finish()) as ArrayRef)
Ok(Arc::new(array))
}

#[cfg(test)]
Expand Down