Added l2_normalize function for sparsevec

README.md

@@ -952,6 +952,7 @@ inner_product(sparsevec, sparsevec) → double precision | inner product | unrel
 l1_distance(sparsevec, sparsevec) → double precision | taxicab distance | unreleased
 l2_distance(sparsevec, sparsevec) → double precision | Euclidean distance | unreleased
 l2_norm(sparsevec) → double precision | Euclidean norm | unreleased
+l2_normalize(sparsevec) → sparsevec | Normalize with Euclidean norm | unreleased
 
 ## Installation Notes - Linux and Mac
 

sql/vector--0.6.2--0.7.0.sql

@@ -364,6 +364,9 @@ CREATE FUNCTION l1_distance(sparsevec, sparsevec) RETURNS float8
 CREATE FUNCTION l2_norm(sparsevec) RETURNS float8
 	AS 'MODULE_PATHNAME', 'sparsevec_l2_norm' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
+CREATE FUNCTION l2_normalize(sparsevec) RETURNS sparsevec
+	AS 'MODULE_PATHNAME', 'sparsevec_l2_normalize' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
 CREATE FUNCTION sparsevec_lt(sparsevec, sparsevec) RETURNS bool
 	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 

sql/vector.sql

@@ -673,6 +673,9 @@ CREATE FUNCTION l1_distance(sparsevec, sparsevec) RETURNS float8
 CREATE FUNCTION l2_norm(sparsevec) RETURNS float8
 	AS 'MODULE_PATHNAME', 'sparsevec_l2_norm' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
+CREATE FUNCTION l2_normalize(sparsevec) RETURNS sparsevec
+	AS 'MODULE_PATHNAME', 'sparsevec_l2_normalize' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
 -- sparsevec private functions
 
 CREATE FUNCTION sparsevec_lt(sparsevec, sparsevec) RETURNS bool

src/hnswutils.c

@@ -213,20 +213,7 @@ HnswNormValue(FmgrInfo *procinfo, Oid collation, Datum *value, HnswType type)
 		else if (type == HNSW_TYPE_HALFVEC)
 			*value = DirectFunctionCall1(halfvec_l2_normalize, *value);
 		else if (type == HNSW_TYPE_SPARSEVEC)
-		{
+			*value = DirectFunctionCall1(sparsevec_l2_normalize, *value);
-			SparseVector *v = DatumGetSparseVector(*value);
-			SparseVector *result = InitSparseVector(v->dim, v->nnz);
-			float	   *vx = SPARSEVEC_VALUES(v);
-			float	   *rx = SPARSEVEC_VALUES(result);
-
-			for (int i = 0; i < v->nnz; i++)
-			{
-				result->indices[i] = v->indices[i];
-				rx[i] = vx[i] / norm;
-			}
-
-			*value = PointerGetDatum(result);
-		}
 		else
 			elog(ERROR, "Unsupported type");
 

src/sparsevec.c

@@ -848,6 +848,48 @@ sparsevec_l2_norm(PG_FUNCTION_ARGS)
 	PG_RETURN_FLOAT8(sqrt(norm));
 }
 
+/*
+ * Normalize a sparse vector with the L2 norm
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(sparsevec_l2_normalize);
+Datum
+sparsevec_l2_normalize(PG_FUNCTION_ARGS)
+{
+	SparseVector *a = PG_GETARG_SPARSEVEC_P(0);
+	float	   *ax = SPARSEVEC_VALUES(a);
+	double		norm = 0;
+	SparseVector *result;
+	float	   *rx;
+
+	result = InitSparseVector(a->dim, a->nnz);
+	rx = SPARSEVEC_VALUES(result);
+
+	/* Auto-vectorized */
+	for (int i = 0; i < a->nnz; i++)
+		norm += (double) ax[i] * (double) ax[i];
+
+	norm = sqrt(norm);
+
+	/* Return zero vector for zero norm */
+	if (norm > 0)
+	{
+		for (int i = 0; i < a->nnz; i++)
+		{
+			result->indices[i] = a->indices[i];
+			rx[i] = ax[i] / norm;
+		}
+
+		/* Check for overflow */
+		for (int i = 0; i < a->nnz; i++)
+		{
+			if (isinf(rx[i]))
+				float_overflow_error();
+		}
+	}
+
+	PG_RETURN_POINTER(result);
+}
+
 /*
  * Internal helper to compare sparse vectors
  */

src/sparsevec.h

@@ -1,6 +1,8 @@
 #ifndef SPARSEVEC_H
 #define SPARSEVEC_H
 
+#include "fmgr.h"
+
 #define SPARSEVEC_MAX_DIM 100000
 #define SPARSEVEC_MAX_NNZ 16000
 
@@ -21,5 +23,6 @@ typedef struct SparseVector
 }			SparseVector;
 
 SparseVector *InitSparseVector(int dim, int nnz);
+Datum		sparsevec_l2_normalize(PG_FUNCTION_ARGS);
 
 #endif

test/expected/sparsevec_functions.out

@@ -292,3 +292,33 @@ SELECT l1_distance('{1:1,3:3,5:5,7:7,9:9}/9'::sparsevec, '{2:2,4:4,6:6,8:8}/9');
           45
 (1 row)
 
+SELECT l2_normalize('{1:3,2:4}/2'::sparsevec);
+  l2_normalize   
+-----------------
+ {1:0.6,2:0.8}/2
+(1 row)
+
+SELECT l2_normalize('{1:3}/2'::sparsevec);
+ l2_normalize 
+--------------
+ {1:1}/2
+(1 row)
+
+SELECT l2_normalize('{2:0.1}/2'::sparsevec);
+ l2_normalize 
+--------------
+ {2:1}/2
+(1 row)
+
+SELECT l2_normalize('{}/2'::sparsevec);
+ l2_normalize 
+--------------
+ {}/2
+(1 row)
+
+SELECT l2_normalize('{1:3e38}/1'::sparsevec);
+ l2_normalize 
+--------------
+ {1:1}/1
+(1 row)
+

test/sql/sparsevec_functions.sql

@@ -55,3 +55,9 @@ SELECT l1_distance('{1:1,2:2}/2'::sparsevec, '{1:3}/1');
 SELECT l1_distance('{1:3e38}/1'::sparsevec, '{1:-3e38}/1');
 SELECT l1_distance('{1:1,3:3,5:5,7:7}/8'::sparsevec, '{2:2,4:4,6:6,8:8}/8');
 SELECT l1_distance('{1:1,3:3,5:5,7:7,9:9}/9'::sparsevec, '{2:2,4:4,6:6,8:8}/9');
+
+SELECT l2_normalize('{1:3,2:4}/2'::sparsevec);
+SELECT l2_normalize('{1:3}/2'::sparsevec);
+SELECT l2_normalize('{2:0.1}/2'::sparsevec);
+SELECT l2_normalize('{}/2'::sparsevec);
+SELECT l2_normalize('{1:3e38}/1'::sparsevec);