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improve BytesRefHash.sort performance by rearranging ids #15772

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Merged
dweiss merged 6 commits into from
Feb 28, 2026
Merged

improve BytesRefHash.sort performance by rearranging ids #15772

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c8d3b74
improve BytesRefHash.sort performance
tyronecai Feb 26, 2026
8b1ee31
Update changes.
tyronecai Feb 27, 2026
f639564
add comment in compact
tyronecai Feb 27, 2026
6e55692
Fix comment typo in compact method
tyronecai Feb 27, 2026
602135c
update comment
tyronecai Feb 27, 2026
8dab310
merge with main.
dweiss Feb 28, 2026
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2 changes: 2 additions & 0 deletions lucene/CHANGES.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -235,6 +235,8 @@ Optimizations

* GITHUB#15729: Lucene90DocValuesProducer is not prefetching any data for DocValueSkippers anymore (Alexander Reelsen)

* GITHUB#15772: improve BytesRefHash.sort performance by rearranging ids#15772 (tyronecai)

* GITHUB#15742: Optimize int4 dotProduct and squareDistance computations by replacing vector conversions with reinterpret casting + bit manipulation. (Trevor McCulloch, Kaival Parikh)

Bug Fixes
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15 changes: 5 additions & 10 deletions lucene/core/src/java/org/apache/lucene/util/BytesRefHash.java
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Expand Up @@ -178,18 +178,13 @@ public BytesRef get(int bytesID, BytesRef ref) {
*/
public int[] compact() {
assert bytesStart != null : "bytesStart is null - not initialized";
int upto = 0;
for (int i = 0; i < hashSize; i++) {
if (ids[i] != -1) {
ids[upto] = ids[i] & hashMask;
if (upto < i) {
ids[i] = -1;
}
upto++;
}

// id is the sequence number when bytes added to the pool
for (int i = 0; i < count; i++) {
ids[i] = i;
}
Arrays.fill(ids, count, hashSize, -1);

assert upto == count;
lastCount = count;
return ids;
}
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