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Optimize performance of substr_index and add tests #9973

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merged 9 commits into from
Apr 8, 2024
Merged

Optimize performance of substr_index and add tests #9973

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ef36090
Optimize performance of substr_index
kevinmingtarja Apr 6, 2024
94b8de2
Add tests for substr_index
kevinmingtarja Apr 6, 2024
cd4cbbc
cargo clippy
kevinmingtarja Apr 6, 2024
abbbea2
Use StringBuilder to avoid String creation in the iterator
kevinmingtarja Apr 6, 2024
89261d7
Add more tests
kevinmingtarja Apr 6, 2024
06e8ace
cargo clippy
kevinmingtarja Apr 6, 2024
14e91bf
Append null if builder is empty
kevinmingtarja Apr 6, 2024
8bdfb36
Fix handling of non matching rows
kevinmingtarja Apr 7, 2024
421f6d9
Refactor test
kevinmingtarja Apr 7, 2024
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153 changes: 133 additions & 20 deletions datafusion/functions/src/unicode/substrindex.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@
use std::any::Any;
use std::sync::Arc;

use arrow::array::{ArrayRef, GenericStringArray, OffsetSizeTrait};
use arrow::array::{ArrayRef, OffsetSizeTrait, StringBuilder};
use arrow::datatypes::DataType;

use datafusion_common::cast::{as_generic_string_array, as_int64_array};
Expand Down Expand Up @@ -101,38 +101,151 @@ pub fn substr_index<T: OffsetSizeTrait>(args: &[ArrayRef]) -> Result<ArrayRef> {
let delimiter_array = as_generic_string_array::<T>(&args[1])?;
let count_array = as_int64_array(&args[2])?;

let result = string_array
let mut builder = StringBuilder::new();
string_array
.iter()
.zip(delimiter_array.iter())
.zip(count_array.iter())
.map(|((string, delimiter), n)| match (string, delimiter, n) {
.for_each(|((string, delimiter), n)| match (string, delimiter, n) {
(Some(string), Some(delimiter), Some(n)) => {
// In MySQL, these cases will return an empty string.
if n == 0 || string.is_empty() || delimiter.is_empty() {
return Some(String::new());
builder.append_value("");
return;
}

let splitted: Box<dyn Iterator<Item = _>> = if n > 0 {
Box::new(string.split(delimiter))
let occurrences = usize::try_from(n.unsigned_abs()).unwrap_or(usize::MAX);
let length = if n > 0 {
let splitted = string.split(delimiter);
splitted
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.take(occurrences)
.map(|s| s.len() + delimiter.len())
.sum::<usize>()
- delimiter.len()
} else {
Box::new(string.rsplit(delimiter))
let splitted = string.rsplit(delimiter);
splitted
.take(occurrences)
.map(|s| s.len() + delimiter.len())
.sum::<usize>()
- delimiter.len()
};
let occurrences = usize::try_from(n.unsigned_abs()).unwrap_or(usize::MAX);
// The length of the substring covered by substr_index.
let length = splitted
.take(occurrences) // at least 1 element, since n != 0
.map(|s| s.len() + delimiter.len())
.sum::<usize>()
- delimiter.len();
if n > 0 {
Some(string[..length].to_owned())
match string.get(..length) {
Some(substring) => builder.append_value(substring),
None => builder.append_null(),
}
} else {
Some(string[string.len() - length..].to_owned())
match string.get(string.len().saturating_sub(length)..) {
Some(substring) => builder.append_value(substring),
None => builder.append_null(),
}
}
}
_ => None,
})
.collect::<GenericStringArray<T>>();
_ => builder.append_null(),
});

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

Ok(Arc::new(result) as ArrayRef)
#[cfg(test)]
mod tests {
use arrow::array::{Array, StringArray};
use arrow::datatypes::DataType::Utf8;

use datafusion_common::{Result, ScalarValue};
use datafusion_expr::{ColumnarValue, ScalarUDFImpl};

use crate::unicode::substrindex::SubstrIndexFunc;
use crate::utils::test::test_function;

#[test]
fn test_functions() -> Result<()> {
test_function!(
SubstrIndexFunc::new(),
&[
ColumnarValue::Scalar(ScalarValue::from("www.apache.org")),
ColumnarValue::Scalar(ScalarValue::from(".")),
ColumnarValue::Scalar(ScalarValue::from(1i64)),
],
Ok(Some("www")),
&str,
Utf8,
StringArray
);
test_function!(
SubstrIndexFunc::new(),
&[
ColumnarValue::Scalar(ScalarValue::from("www.apache.org")),
ColumnarValue::Scalar(ScalarValue::from(".")),
ColumnarValue::Scalar(ScalarValue::from(2i64)),
],
Ok(Some("www.apache")),
&str,
Utf8,
StringArray
);
test_function!(
SubstrIndexFunc::new(),
&[
ColumnarValue::Scalar(ScalarValue::from("www.apache.org")),
ColumnarValue::Scalar(ScalarValue::from(".")),
ColumnarValue::Scalar(ScalarValue::from(-2i64)),
],
Ok(Some("apache.org")),
&str,
Utf8,
StringArray
);
test_function!(
SubstrIndexFunc::new(),
&[
ColumnarValue::Scalar(ScalarValue::from("www.apache.org")),
ColumnarValue::Scalar(ScalarValue::from(".")),
ColumnarValue::Scalar(ScalarValue::from(-1i64)),
],
Ok(Some("org")),
&str,
Utf8,
StringArray
);
test_function!(
SubstrIndexFunc::new(),
&[
ColumnarValue::Scalar(ScalarValue::from("www.apache.org")),
ColumnarValue::Scalar(ScalarValue::from(".")),
ColumnarValue::Scalar(ScalarValue::from(0i64)),
],
Ok(Some("")),
&str,
Utf8,
StringArray
);
test_function!(
SubstrIndexFunc::new(),
&[
ColumnarValue::Scalar(ScalarValue::from("")),
ColumnarValue::Scalar(ScalarValue::from(".")),
ColumnarValue::Scalar(ScalarValue::from(1i64)),
],
Ok(Some("")),
&str,
Utf8,
StringArray
);
test_function!(
SubstrIndexFunc::new(),
&[
ColumnarValue::Scalar(ScalarValue::from("www.apache.org")),
ColumnarValue::Scalar(ScalarValue::from("")),
ColumnarValue::Scalar(ScalarValue::from(1i64)),
],
Ok(Some("")),
&str,
Utf8,
StringArray
);

Ok(())
}
}
11 changes: 10 additions & 1 deletion datafusion/sqllogictest/test_files/functions.slt
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Original file line number Diff line number Diff line change
Expand Up @@ -940,7 +940,8 @@ SELECT str, n, substring_index(str, '.', n) AS c FROM
(VALUES
ROW('arrow.apache.org'),
ROW('.'),
ROW('...')
ROW('...'),
ROW(NULL)
) AS strings(str),
(VALUES
ROW(1),
Expand All @@ -954,6 +955,14 @@ SELECT str, n, substring_index(str, '.', n) AS c FROM
) AS occurrences(n)
ORDER BY str DESC, n;
----
NULL -100 NULL
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NULL -3 NULL
NULL -2 NULL
NULL -1 NULL
NULL 1 NULL
NULL 2 NULL
NULL 3 NULL
NULL 100 NULL
arrow.apache.org -100 arrow.apache.org
arrow.apache.org -3 arrow.apache.org
arrow.apache.org -2 apache.org
Expand Down
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