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fix: shuffle seed #18518

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merged 2 commits into from
Nov 8, 2025
+103 −45
Merged

fix: shuffle seed #18518

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fcdb8ba
fix: seed
chenkovsky Nov 6, 2025
03be0c7
update
chenkovsky Nov 7, 2025
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102 changes: 88 additions & 14 deletions datafusion/spark/src/function/array/shuffle.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,21 +15,25 @@
// specific language governing permissions and limitations
// under the License.

use crate::function::functions_nested_utils::make_scalar_function;
use arrow::array::{
Array, ArrayRef, Capacities, FixedSizeListArray, GenericListArray, MutableArrayData,
OffsetSizeTrait,
};
use arrow::buffer::OffsetBuffer;
use arrow::datatypes::DataType;
use arrow::datatypes::DataType::{FixedSizeList, LargeList, List, Null};
use arrow::datatypes::{DataType, FieldRef};
use arrow::datatypes::FieldRef;
use datafusion_common::cast::{
as_fixed_size_list_array, as_large_list_array, as_list_array,
};
use datafusion_common::{exec_err, utils::take_function_args, Result};
use datafusion_expr::{ColumnarValue, ScalarUDFImpl, Signature, Volatility};
use datafusion_common::{exec_err, utils::take_function_args, Result, ScalarValue};
use datafusion_expr::{
ArrayFunctionArgument, ArrayFunctionSignature, ColumnarValue, ScalarUDFImpl,
Signature, TypeSignature, Volatility,
};
use rand::rng;
use rand::seq::SliceRandom;
use rand::rngs::StdRng;
use rand::{seq::SliceRandom, Rng, SeedableRng};
use std::any::Any;
use std::sync::Arc;

Expand All @@ -47,7 +51,25 @@ impl Default for SparkShuffle {
impl SparkShuffle {
pub fn new() -> Self {
Self {
signature: Signature::arrays(1, None, Volatility::Volatile),
signature: Signature {
type_signature: TypeSignature::OneOf(vec![
// Only array argument
TypeSignature::ArraySignature(ArrayFunctionSignature::Array {
arguments: vec![ArrayFunctionArgument::Array],
array_coercion: None,
}),
// Array + Index (seed) argument
TypeSignature::ArraySignature(ArrayFunctionSignature::Array {
arguments: vec![
ArrayFunctionArgument::Array,
ArrayFunctionArgument::Index,
],
array_coercion: None,
}),
]),
volatility: Volatility::Volatile,
parameter_names: None,
},
}
}
}
Expand All @@ -73,25 +95,63 @@ impl ScalarUDFImpl for SparkShuffle {
&self,
args: datafusion_expr::ScalarFunctionArgs,
) -> Result<ColumnarValue> {
make_scalar_function(array_shuffle_inner)(&args.args)
if args.args.is_empty() {
return exec_err!("shuffle expects at least 1 argument");
}
if args.args.len() > 2 {
return exec_err!("shuffle expects at most 2 arguments");
}

// Extract seed from second argument if present
let seed = if args.args.len() == 2 {
extract_seed(&args.args[1])?
} else {
None
};

// Convert arguments to arrays
let arrays = ColumnarValue::values_to_arrays(&args.args[..1])?;
array_shuffle_with_seed(&arrays, seed).map(ColumnarValue::Array)
}
}

/// Extract seed value from ColumnarValue
fn extract_seed(seed_arg: &ColumnarValue) -> Result<Option<u64>> {
match seed_arg {
ColumnarValue::Scalar(scalar) => {
let seed = match scalar {
ScalarValue::Int64(Some(v)) => Some(*v as u64),
ScalarValue::Null => None,
_ => {
return exec_err!(
"shuffle seed must be Int64 type, got '{}'",
scalar.data_type()
);
}
};
Ok(seed)
}
ColumnarValue::Array(_) => {
exec_err!("shuffle seed must be a scalar value, not an array")
}
}
}

/// array_shuffle SQL function
pub fn array_shuffle_inner(arg: &[ArrayRef]) -> Result<ArrayRef> {
/// array_shuffle SQL function with optional seed
fn array_shuffle_with_seed(arg: &[ArrayRef], seed: Option<u64>) -> Result<ArrayRef> {
let [input_array] = take_function_args("shuffle", arg)?;
match &input_array.data_type() {
List(field) => {
let array = as_list_array(input_array)?;
general_array_shuffle::<i32>(array, field)
general_array_shuffle::<i32>(array, field, seed)
}
LargeList(field) => {
let array = as_large_list_array(input_array)?;
general_array_shuffle::<i64>(array, field)
general_array_shuffle::<i64>(array, field, seed)
}
FixedSizeList(field, _) => {
let array = as_fixed_size_list_array(input_array)?;
fixed_size_array_shuffle(array, field)
fixed_size_array_shuffle(array, field, seed)
}
Null => Ok(Arc::clone(input_array)),
array_type => exec_err!("shuffle does not support type '{array_type}'."),
Expand All @@ -101,6 +161,7 @@ pub fn array_shuffle_inner(arg: &[ArrayRef]) -> Result<ArrayRef> {
fn general_array_shuffle<O: OffsetSizeTrait>(
array: &GenericListArray<O>,
field: &FieldRef,
seed: Option<u64>,
) -> Result<ArrayRef> {
let values = array.values();
let original_data = values.to_data();
Expand All @@ -109,7 +170,13 @@ fn general_array_shuffle<O: OffsetSizeTrait>(
let mut nulls = vec![];
let mut mutable =
MutableArrayData::with_capacities(vec![&original_data], false, capacity);
let mut rng = rng();
let mut rng = if let Some(s) = seed {
StdRng::seed_from_u64(s)
} else {
// Use a random seed from the thread-local RNG
let seed = rng().random::<u64>();
StdRng::seed_from_u64(seed)
};

for (row_index, offset_window) in array.offsets().windows(2).enumerate() {
// skip the null value
Expand Down Expand Up @@ -149,6 +216,7 @@ fn general_array_shuffle<O: OffsetSizeTrait>(
fn fixed_size_array_shuffle(
array: &FixedSizeListArray,
field: &FieldRef,
seed: Option<u64>,
) -> Result<ArrayRef> {
let values = array.values();
let original_data = values.to_data();
Expand All @@ -157,7 +225,13 @@ fn fixed_size_array_shuffle(
let mut mutable =
MutableArrayData::with_capacities(vec![&original_data], false, capacity);
let value_length = array.value_length() as usize;
let mut rng = rng();
let mut rng = if let Some(s) = seed {
StdRng::seed_from_u64(s)
} else {
// Use a random seed from the thread-local RNG
let seed = rng().random::<u64>();
StdRng::seed_from_u64(seed)
};

for row_index in 0..array.len() {
// skip the null value
Expand Down
46 changes: 15 additions & 31 deletions datafusion/sqllogictest/test_files/spark/array/shuffle.slt
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Original file line number Diff line number Diff line change
Expand Up @@ -16,27 +16,16 @@
# under the License.

# Test shuffle function with simple arrays
query B
SELECT array_sort(shuffle([1, 2, 3, 4, 5, NULL])) = [NULL,1, 2, 3, 4, 5];
----
true

query B
SELECT shuffle([1, 2, 3, 4, 5, NULL]) != [1, 2, 3, 4, 5, NULL];
query ?
SELECT shuffle([1, 2, 3, 4, 5, NULL], 1);
----
true
[1, 4, NULL, 2, 5, 3]

# Test shuffle function with string arrays

query B
SELECT array_sort(shuffle(['a', 'b', 'c', 'd', 'e', 'f'])) = ['a', 'b', 'c', 'd', 'e', 'f'];
----
true

query B
SELECT shuffle(['a', 'b', 'c', 'd', 'e', 'f']) != ['a', 'b', 'c', 'd', 'e', 'f'];;
query ?
SELECT shuffle(['a', 'b', 'c', 'd', 'e', 'f'], 1);
----
true
[a, d, f, b, e, c]

# Test shuffle function with empty array
query ?
Expand All @@ -57,15 +46,10 @@ SELECT shuffle(NULL);
NULL

# Test shuffle function with fixed size list arrays
query B
SELECT array_sort(shuffle(arrow_cast([1, 2, NULL, 3, 4, 5], 'FixedSizeList(6, Int64)'))) = [NULL, 1, 2, 3, 4, 5];
----
true

query B
SELECT shuffle(arrow_cast([1, 2, NULL, 3, 4, 5], 'FixedSizeList(6, Int64)')) != [1, 2, NULL, 3, 4, 5];
query ?
SELECT shuffle(arrow_cast([1, 2, NULL, 3, 4, 5], 'FixedSizeList(6, Int64)'), 1);
----
true
[1, 3, 5, 2, 4, NULL]

# Test shuffle on table data with different list types
statement ok
Expand All @@ -78,10 +62,10 @@ CREATE TABLE test_shuffle_list_types AS VALUES

# Test shuffle with large list from table
query ?
SELECT array_sort(shuffle(column1)) FROM test_shuffle_list_types;
SELECT shuffle(column1, 1) FROM test_shuffle_list_types;
----
[1, 2, 3, 4]
[5, 6, 7, 8, 9]
[1, 4, 3, 2]
[8, 9, 6, 5, 7]
[10]
NULL
[]
Expand All @@ -96,11 +80,11 @@ CREATE TABLE test_shuffle_fixed_size AS VALUES

# Test shuffle with fixed size list from table
query ?
SELECT array_sort(shuffle(column1)) FROM test_shuffle_fixed_size;
SELECT shuffle(column1, 1) FROM test_shuffle_fixed_size;
----
[1, 2, 3]
[4, 5, 6]
[NULL, 8, 9]
[4, 6, 5]
[9, NULL, 8]
NULL

# Clean up
Expand Down