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perf: combine_hashes for primitive multi-column rehash #22350

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perf: combine_hashes for primitive multi-column rehash #22350

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13 changes: 5 additions & 8 deletions datafusion/common/src/hash_utils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -211,8 +211,8 @@ fn seeded_state(seed: u64) -> foldhash::fast::SeedableRandomState {
}

/// Builds hash values of PrimitiveArray and writes them into `hashes_buffer`
/// If `rehash==true` this folds the existing hash into the hasher state
/// and hashes only the new value (avoiding a separate combine step).
/// If `rehash==true` this combines the previous hash value in the buffer
/// with the new hash using `combine_hashes`.
#[cfg(not(feature = "force_hash_collisions"))]
fn hash_array_primitive<T>(
array: &PrimitiveArray<T>,
Expand All @@ -231,9 +231,7 @@ fn hash_array_primitive<T>(
if array.null_count() == 0 {
if rehash {
for (hash, &value) in hashes_buffer.iter_mut().zip(array.values().iter()) {
let mut hasher = seeded_state(*hash).build_hasher();
value.hash_write(&mut hasher);
*hash = hasher.finish();
*hash = combine_hashes(value.hash_one(random_state), *hash);
}
} else {
for (hash, &value) in hashes_buffer.iter_mut().zip(array.values().iter()) {
Expand All @@ -243,9 +241,8 @@ fn hash_array_primitive<T>(
} else if rehash {
for i in array.nulls().unwrap().valid_indices() {
let value = unsafe { array.value_unchecked(i) };
let mut hasher = seeded_state(hashes_buffer[i]).build_hasher();
value.hash_write(&mut hasher);
hashes_buffer[i] = hasher.finish();
hashes_buffer[i] =
combine_hashes(value.hash_one(random_state), hashes_buffer[i]);
}
} else {
for i in array.nulls().unwrap().valid_indices() {
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