iprithv commented on code in PR #16068:
URL: https://github.com/apache/lucene/pull/16068#discussion_r3312506089
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lucene/sandbox/src/java/org/apache/lucene/sandbox/codecs/faiss/FaissLibraryNativeImpl.java:
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@@ -277,29 +265,39 @@ private interface FloatToFloatFunction {
private final FloatToFloatFunction scaler;
private boolean closed;
- private Index(MemorySegment indexPointer) {
+ private Index(
+ MemorySegment indexPointer, VectorSimilarityFunction function,
VectorEncoding encoding) {
this.arena = Arena.ofShared();
this.indexPointer =
indexPointer
// Ensure timely cleanup
.reinterpret(arena, wrapper::faiss_Index_free);
- // Get underlying function
- int metricType = wrapper.faiss_Index_metric_type(indexPointer);
- VectorSimilarityFunction function = metricToFunction(metricType);
+ int dimension = wrapper.faiss_Index_d(indexPointer);
// Scale Faiss distances to Lucene scores, see
VectorSimilarityFunction.java
this.scaler =
switch (function) {
- case DOT_PRODUCT ->
- // distance in Faiss === dotProduct in Lucene
- distance -> Math.max((1 + distance) / 2, 0);
+ case DOT_PRODUCT -> {
+ if (encoding == VectorEncoding.BYTE) {
+ float denom = (float) (dimension * (1 << 15));
+ yield distance -> 0.5f + distance / denom;
+ } else {
+ yield distance -> Math.max((1 + distance) / 2, 0);
Review Comment:
understood, done. thanks!
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