Details
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Bug
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Status: Closed (View Workflow)
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Minor
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Resolution: Won't Fix
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11.8.1
Description
sql: SELECT VEC_DISTANCE_COSINE(VEC_FROMTEXT('[1,2,3]'), VEC_FROMTEXT('[0,0,0]'));
return value is 0.
static double calc_distance_cosine(float *v1, float *v2, size_t v_len) |
{
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double dotp=0, abs1=0, abs2=0; |
for (size_t i= 0; i < v_len; i++, v1++, v2++) |
{
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float f1= get_float(v1), f2= get_float(v2); |
abs1+= f1 * f1;
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abs2+= f2 * f2;
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dotp+= f1 * f2;
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}
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return 1 - dotp/sqrt(abs1*abs2); |
}
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abs1 or abs2 maybe zero, so in this case，1 should be returned
Attachments
Issue Links
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Activity
I run ann bench mark with dataset nytimes-256-angular, this is zero data in dataset
Right, the operation is undefined, 1 it no better than 0 here.
And, right, ann-benchmarks has 239 such vectors. But, again, because the distance for them isn't defined, one cannot say whether they're close to anything or not. They shouldn't cause bugs thpough — like data corruption, wrong results (for other vectors) or crashes.
MDEV-36317 claims that returning a particular value significantly improves the recall on the nytimes-256-angular data set. This will be investigated in MDEV-36317
This operation is undefined, you can't calculate cosine distance when either vectors is the 0 vector.