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MDEV-39858: Reloading COSINE metric index from disk degrades search r… #5184

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Merged
vuvova merged 1 commit into from
Aug 7, 2026
+8 −8
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MDEV-39858: Reloading COSINE metric index from disk degrades search r… #5184

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16 changes: 8 additions & 8 deletions sql/vector_mhnsw.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,8 @@ struct FVector
vec->scale= std::nextafter(vec->scale, FLT_MAX);
for (size_t i= 0; i < vec_len; i++)
vec->dims[i] = static_cast<int16_t>(std::round(get_float(v + i) / vec->scale));
vec->postprocess(vec_len);
vec->fix_tail(vec_len);
vec->abs2= vec->scale * vec->scale * dot_product(vec->dims, vec->dims, vec_len) / 2;
if (metric == COSINE)
{
if (vec->abs2 > 0.0f)
Expand All @@ -113,12 +114,6 @@ struct FVector
return vec;
}

void postprocess(size_t vec_len)
{
fix_tail(vec_len);
abs2= scale * scale * dot_product(dims, dims, vec_len) / 2;
}

#ifdef AVX2_IMPLEMENTATION
/************* AVX2 *****************************************************/
static constexpr size_t AVX2_bytes= 256/8;
Expand Down Expand Up @@ -882,7 +877,12 @@ int FVectorNode::load_from_record(TABLE *graph)
return my_errno= HA_ERR_CRASHED;
FVector *vec_ptr= FVector::align_ptr(tref() + tref_len());
memcpy(vec_ptr->data(), v->ptr(), v->length());
vec_ptr->postprocess(ctx->vec_len);
vec_ptr->fix_tail(ctx->vec_len);
if (ctx->metric == COSINE)
vec_ptr->abs2= 0.5f;
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else
vec_ptr->abs2= vec_ptr->scale * vec_ptr->scale *
vec_ptr->dot_product(vec_ptr->dims, vec_ptr->dims, ctx->vec_len) / 2;

longlong layer= graph->field[FIELD_LAYER]->val_int();
if (layer > 100) // 10e30 nodes at M=2, more at larger M's
Expand Down