This is an automated email from the ASF dual-hosted git repository.
Jefffrey pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/arrow-rs.git
The following commit(s) were added to refs/heads/main by this push:
new bb82f3e4fc bench(arrow): add sparse dictionary to view cast benchmarks
(#10596)
bb82f3e4fc is described below
commit bb82f3e4fcb99cea6c730e906c067579802593fe
Author: Abhishek <[email protected]>
AuthorDate: Mon Aug 10 04:47:27 2026 +0530
bench(arrow): add sparse dictionary to view cast benchmarks (#10596)
# Which issue does this PR close?
<!--
We generally require a GitHub issue to be filed for all bug fixes and
enhancements and this helps us generate change logs for our releases.
You can link an issue to this PR using the GitHub syntax.
-->
None. Split out of #10436 at review request, so these land on main first
and the bot can measure that PR against them.
# Rationale for this change
<!--
Why are you proposing this change? If this is already explained clearly
in the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand
your changes and offer better suggestions for fixes.
-->
`cast_kernels` has one dictionary to view benchmark, at 10,000 rows over
3 values. Nothing covers the opposite shape, a dictionary much larger
than the array, and nothing covers `dict<binary> -> utf8view`, which
validates the values as UTF-8.
# What changes are included in this PR?
<!--
There is no need to duplicate the description in the issue here but it
is sometimes worth providing a summary of the individual changes in this
PR.
-->
Two benchmarks, both 1024 rows over 32,768 values:
- `cast dict to string view (sparse)`. For #10436 this is a no
regression check rather than an expected win, since main already takes
the direct path at this shape
- `cast binary dict to string view (sparse)`. No dense counterpart,
since that shape runs the same code either way
Keys come from `seedable_rng` so they spread across the dictionary, and
values exceed 12 bytes so the views reference the buffer rather than
inlining.
# Are these changes tested?
<!--
We typically require tests for all PRs in order to:
1. Prevent the code from being accidentally broken by subsequent changes
2. Serve as another way to document the expected behavior of the code
If tests are not included in your PR, please explain why (for example,
are they covered by existing tests)?
If this PR claims a performance improvement, please include evidence
such as benchmark results.
-->
Benchmarks only, no library code touched. They build and run under
`cargo bench -p arrow --features test_utils --bench cast_kernels`.
# Are there any user-facing changes?
<!--
If there are user-facing changes then we may require documentation to be
updated before approving the PR.
If there are any breaking changes to public APIs, please call them out.
-->
No.
---
arrow/benches/cast_kernels.rs | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/arrow/benches/cast_kernels.rs b/arrow/benches/cast_kernels.rs
index 8afe0238ef..18acbe2d6f 100644
--- a/arrow/benches/cast_kernels.rs
+++ b/arrow/benches/cast_kernels.rs
@@ -202,6 +202,34 @@ fn build_nested_dict_array(size: usize) -> ArrayRef {
Arc::new(DictionaryArray::new(outer_keys, Arc::new(inner)))
}
+// Keys for a `size` row dictionary, spread over `distinct` values so a cast
has to touch
+// the whole values buffer rather than a contiguous prefix of it.
+fn dict_keys(size: usize, distinct: usize) -> UInt64Array {
+ let mut rng = seedable_rng();
+ let range = Uniform::new(0, distinct as u64).unwrap();
+ UInt64Array::from_iter_values((0..size).map(|_| rng.sample(range)))
+}
+
+// `Dictionary<UInt64, Utf8>` of `size` rows over `distinct` values,
alternating between
+// values short enough to inline into a view and longer ones that reference
the buffer.
+//
+// Different implementation paths may be taken based on the ratio of rows to
distinct
+// values.
+fn build_string_dict_array(size: usize, distinct: usize) -> ArrayRef {
+ let values = StringArray::from_iter_values((0..distinct).map(|i| {
+ if i % 2 == 0 {
+ format!("val {i}")
+ } else {
+ format!("dictionary value {i:07}")
+ }
+ }));
+
+ Arc::new(DictionaryArray::new(
+ dict_keys(size, distinct),
+ Arc::new(values),
+ ))
+}
+
// cast array from specified primitive array type to desired data type
fn cast_array(array: &ArrayRef, to_type: DataType) {
hint::black_box(cast(hint::black_box(array),
hint::black_box(&to_type)).unwrap());
@@ -234,6 +262,15 @@ fn add_benchmark(c: &mut Criterion) {
let string_view_array = cast(&dict_array, &DataType::Utf8View).unwrap();
let binary_view_array = cast(&string_view_array,
&DataType::BinaryView).unwrap();
+ // the dictionary is far larger than the array is long, as after a
selective filter.
+ // `dict_array` above is the opposite shape, many rows over few dictionary
values.
+ let sparse_dict_array = build_string_dict_array(1_024, 32_768);
+ let sparse_binary_dict_array = cast(
+ &sparse_dict_array,
+ &DataType::Dictionary(Box::new(DataType::UInt64),
Box::new(DataType::Binary)),
+ )
+ .unwrap();
+
let string_float_array_normal = build_string_float_array(5_000, 0.1);
let float64_array_cast_to_decimal =
build_float64_array_for_cast_to_decimal(8_000, 0.1);
let invalid_float64_array_to_decimal =
build_float64_array_invalid_items(8_000, 0.1);
@@ -352,6 +389,12 @@ fn add_benchmark(c: &mut Criterion) {
c.bench_function("cast dict to string view", |b| {
b.iter(|| cast_array(&dict_array, DataType::Utf8View))
});
+ c.bench_function("cast dict to string view (sparse)", |b| {
+ b.iter(|| cast_array(&sparse_dict_array, DataType::Utf8View))
+ });
+ c.bench_function("cast binary dict to string view (sparse)", |b| {
+ b.iter(|| cast_array(&sparse_binary_dict_array, DataType::Utf8View))
+ });
c.bench_function("cast nested dict to dict", |b| {
b.iter(|| {
cast_array(
