expose vector_distance_l2 func

- we had it before but it's harder to add tests for l2 metric without it

Author: sivukhin

libsql-sqlite3/src/vector.c

@@ -133,6 +133,8 @@ float vectorDistanceL2(const Vector *pVector1, const Vector *pVector2){
       return vectorF32DistanceL2(pVector1, pVector2);
     case VECTOR_TYPE_FLOAT64:
       return vectorF64DistanceL2(pVector1, pVector2);
+    case VECTOR_TYPE_FLOAT8:
+      return vectorF8DistanceL2(pVector1, pVector2);
     default:
       assert(0);
   }
@@ -928,13 +930,11 @@ static void vectorExtractFunc(
   }
 }
 
-/*
-** Implementation of vector_distance_cos(X, Y) function.
-*/
-static void vectorDistanceCosFunc(
+static void vectorDistanceFunc(
   sqlite3_context *context,
   int argc,
-  sqlite3_value **argv
+  sqlite3_value **argv,
+  float (*vectorDistance)(const Vector *pVector1, const Vector *pVector2)
 ){
   char *pzErrMsg = NULL;
   Vector *pVector1 = NULL, *pVector2 = NULL;
@@ -983,7 +983,7 @@ static void vectorDistanceCosFunc(
     sqlite3_free(pzErrMsg);
     goto out_free;
   }
-  sqlite3_result_double(context, vectorDistanceCos(pVector1, pVector2));
+  sqlite3_result_double(context, vectorDistance(pVector1, pVector2));
 out_free:
   if( pVector2 ){
     vectorFree(pVector2);
@@ -993,6 +993,20 @@ static void vectorDistanceCosFunc(
   }
 }
 
+/*
+** Implementation of vector_distance_cos(X, Y) function.
+*/
+static void vectorDistanceCosFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
+  vectorDistanceFunc(context, argc, argv, vectorDistanceCos);
+}
+
+/*
+** Implementation of vector_distance_l2(X, Y) function.
+*/
+static void vectorDistanceL2Func(sqlite3_context *context, int argc, sqlite3_value **argv){
+  vectorDistanceFunc(context, argc, argv, vectorDistanceL2);
+}
+
 /*
  * Marker function which is used in index creation syntax: CREATE INDEX idx ON t(libsql_vector_idx(emb));
 */
@@ -1013,6 +1027,7 @@ void sqlite3RegisterVectorFunctions(void){
     FUNCTION(vector8,             1, 0, 0, vector8Func),
     FUNCTION(vector_extract,      1, 0, 0, vectorExtractFunc),
     FUNCTION(vector_distance_cos, 2, 0, 0, vectorDistanceCosFunc),
+    FUNCTION(vector_distance_l2,  2, 0, 0, vectorDistanceL2Func),
 
     FUNCTION(libsql_vector_idx,  -1, 0, 0, libsqlVectorIdx),
   };

libsql-sqlite3/src/vectorInt.h

@@ -120,6 +120,7 @@ int vector1BitDistanceHamming(const Vector *, const Vector *);
  * Calculates L2 distance between two vectors (vector must have same type and same dimensions)
 */
 float vectorDistanceL2    (const Vector *, const Vector *);
+float vectorF8DistanceL2  (const Vector *, const Vector *);
 float vectorF32DistanceL2 (const Vector *, const Vector *);
 double vectorF64DistanceL2(const Vector *, const Vector *);
 

libsql-sqlite3/src/vectorfloat8.c

@@ -123,11 +123,23 @@ float vectorF8DistanceCos(const Vector *v1, const Vector *v2){
 }
 
 float vectorF8DistanceL2(const Vector *v1, const Vector *v2){
+  int i;
+  float alpha1, shift1, alpha2, shift2;
+  float sum = 0;
+  u8 *data1 = v1->data, *data2 = v2->data;
+
   assert( v1->dims == v2->dims );
   assert( v1->type == VECTOR_TYPE_FLOAT8 );
   assert( v2->type == VECTOR_TYPE_FLOAT8 );
 
-  assert( 0 );
+  vectorF8GetParameters(v1->data, v1->dims, &alpha1, &shift1);
+  vectorF8GetParameters(v2->data, v2->dims, &alpha2, &shift2);
+
+  for(i = 0; i < v1->dims; i++){
+    float d = (alpha1 * data1[i] + shift1) - (alpha2 * data2[i] + shift2);
+    sum += d*d;
+  }
+  return sqrt(sum);
 }
 
 void vectorF8DeserializeFromBlob(