Exclude zero vectors for cosine distance to be consistent with other types [skip ci]

sql/vector--0.6.2--0.7.0.sql

@@ -39,6 +39,9 @@ CREATE FUNCTION cosine_distance(intvec, intvec) RETURNS float8
 CREATE FUNCTION l1_distance(intvec, intvec) RETURNS float8
 	AS 'MODULE_PATHNAME', 'intvec_l1_distance' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
+CREATE FUNCTION l2_norm(intvec) RETURNS float8
+	AS 'MODULE_PATHNAME', 'intvec_l2_norm' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
 CREATE FUNCTION intvec_l2_squared_distance(intvec, intvec) RETURNS float8
 	AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
@@ -85,4 +88,5 @@ CREATE OPERATOR CLASS intvec_ip_ops
 CREATE OPERATOR CLASS intvec_cosine_ops
 	FOR TYPE intvec USING hnsw AS
 	OPERATOR 1 <=> (intvec, intvec) FOR ORDER BY float_ops,
-	FUNCTION 1 cosine_distance(intvec, intvec);
+	FUNCTION 1 cosine_distance(intvec, intvec),
+	FUNCTION 2 l2_norm(intvec);

sql/vector.sql

@@ -330,6 +330,9 @@ CREATE FUNCTION cosine_distance(intvec, intvec) RETURNS float8
 CREATE FUNCTION l1_distance(intvec, intvec) RETURNS float8
 	AS 'MODULE_PATHNAME', 'intvec_l1_distance' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
+CREATE FUNCTION l2_norm(intvec) RETURNS float8
+	AS 'MODULE_PATHNAME', 'intvec_l2_norm' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
 -- intvec private functions
 
 CREATE FUNCTION intvec_l2_squared_distance(intvec, intvec) RETURNS float8
@@ -386,4 +389,5 @@ CREATE OPERATOR CLASS intvec_ip_ops
 CREATE OPERATOR CLASS intvec_cosine_ops
 	FOR TYPE intvec USING hnsw AS
 	OPERATOR 1 <=> (intvec, intvec) FOR ORDER BY float_ops,
-	FUNCTION 1 cosine_distance(intvec, intvec);
+	FUNCTION 1 cosine_distance(intvec, intvec),
+	FUNCTION 2 l2_norm(intvec);

src/hnswutils.c

@@ -204,6 +204,10 @@ HnswNormValue(FmgrInfo *procinfo, Oid collation, Datum *value, HnswType type)
 
 			*value = PointerGetDatum(result);
 		}
+		else if (type == HNSW_TYPE_INTVEC)
+		{
+			/* Do nothing */
+		}
 		else
 			elog(ERROR, "Unsupported type");
 

src/intvec.c

@@ -588,3 +588,21 @@ intvec_l1_distance(PG_FUNCTION_ARGS)
 
 	PG_RETURN_FLOAT8((double) distance);
 }
+
+/*
+ * Get the L2 norm of an int vector
+ */
+PGDLLEXPORT PG_FUNCTION_INFO_V1(intvec_l2_norm);
+Datum
+intvec_l2_norm(PG_FUNCTION_ARGS)
+{
+	IntVector  *a = PG_GETARG_INTVEC_P(0);
+	int8	   *ax = a->x;
+	int			norm = 0;
+
+	/* Auto-vectorized */
+	for (int i = 0; i < a->dim; i++)
+		norm += ax[i] * ax[i];
+
+	PG_RETURN_FLOAT8(sqrt((double) norm));
+}

test/expected/hnsw_intvec_cosine.out

@@ -9,19 +9,18 @@ SELECT * FROM t ORDER BY val <=> '[3,3,3]';
  [1,1,1]
  [1,2,3]
  [1,2,4]
- [0,0,0]
+(3 rows)
-(4 rows)
 
 SELECT COUNT(*) FROM (SELECT * FROM t ORDER BY val <=> '[0,0,0]') t2;
  count 
 -------
-     4
+     3
 (1 row)
 
 SELECT COUNT(*) FROM (SELECT * FROM t ORDER BY val <=> (SELECT NULL::intvec)) t2;
  count 
 -------
-     4
+     3
 (1 row)
 
 DROP TABLE t;