Replace vector_l2sq_dist with overloaded l2sq_dist (lanterndata#166)

sql/lantern.sql

@@ -30,13 +30,13 @@ BEGIN
 
 	IF pgvector_exists THEN
 		-- taken from pgvector so our index can work with pgvector types
-		CREATE FUNCTION vector_l2sq_dist(vector, vector) RETURNS float8
-			AS 'MODULE_PATHNAME' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+		CREATE FUNCTION l2sq_dist(vector, vector) RETURNS float8
+			AS 'MODULE_PATHNAME', 'vector_l2sq_dist' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
 
 		CREATE OPERATOR CLASS dist_vec_l2sq_ops
 			DEFAULT FOR TYPE vector USING lantern_hnsw AS
 			OPERATOR 1 <-> (vector, vector) FOR ORDER BY float_ops,
-			FUNCTION 1 vector_l2sq_dist(vector, vector);
+			FUNCTION 1 l2sq_dist(vector, vector);
 	END IF;
 
 
@@ -46,16 +46,6 @@ BEGIN
 		-- create access method
 		CREATE ACCESS METHOD hnsw TYPE INDEX HANDLER hnsw_handler;
 		COMMENT ON ACCESS METHOD hnsw IS 'LanternDB access method for vector embeddings, based on the hnsw algorithm';
-		IF pgvector_exists THEN
-			-- An older version of pgvector exists, which does not have hnsw yet
-			-- So, there is no naming conflict. We still add a compatibility operator class
-			-- so pgvector vector type can be used with our index
-			-- taken from pgvector so our index can work with pgvector types
-			CREATE OPERATOR CLASS dist_vec_l2sq_ops
-				DEFAULT FOR TYPE vector USING hnsw AS
-				OPERATOR 1 <-> (vector, vector) FOR ORDER BY float_ops,
-				FUNCTION 1 vector_l2sq_dist(vector, vector);
-		END IF;
 	END IF;
 END;
 $BODY$

sql/updates/0.0.4-latest.sql

@@ -0,0 +1,15 @@
+-- drop the old implementation
+DROP FUNCTION IF EXISTS vector_l2sq_dist(vector, vector);
+
+-- replace is with overloaded version
+-- Check if the vector type from pgvector exists
+SELECT EXISTS (
+	SELECT 1
+	FROM pg_type
+	WHERE typname = 'vector'
+) INTO pgvector_exists;
+
+IF pgvector_exists THEN
+			CREATE FUNCTION l2sq_dist(vector, vector) RETURNS float8
+					AS 'MODULE_PATHNAME', 'vector_l2sq_dist' LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+END IF

test/expected/hnsw_vector.out

@@ -98,7 +98,7 @@ FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
          Order By: (v <-> '[0,1,0]'::vector)
 (3 rows)
 
-SELECT ROUND(vector_l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
+SELECT ROUND(l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
 FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
  dist 
 ------
@@ -111,7 +111,7 @@ FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
  2.00
 (7 rows)
 
-EXPLAIN (COSTS FALSE) SELECT ROUND(vector_l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
+EXPLAIN (COSTS FALSE) SELECT ROUND(l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
 FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
                        QUERY PLAN                        
 ---------------------------------------------------------
@@ -171,5 +171,5 @@ ERROR:  Operator <-> has no standalone meaning and is reserved for use in vector
 -- Expect error due to mismatching vector dimensions
 SELECT 1 FROM small_world ORDER BY v <-> '[0,1,0,1]' LIMIT 1;
 ERROR:  Expected vector with dimension 3, got 4
-SELECT vector_l2sq_dist('[1,1]'::vector, '[0,1,0]'::vector);
+SELECT l2sq_dist('[1,1]'::vector, '[0,1,0]'::vector);
 ERROR:  expected equally sized vectors but got vectors with dimensions 2 and 3

test/sql/hnsw_vector.sql

@@ -39,9 +39,9 @@ FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
 EXPLAIN (COSTS FALSE) SELECT ROUND(l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
 FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
 
-SELECT ROUND(vector_l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
+SELECT ROUND(l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
 FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
-EXPLAIN (COSTS FALSE) SELECT ROUND(vector_l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
+EXPLAIN (COSTS FALSE) SELECT ROUND(l2sq_dist(v, '[0,1,0]'::VECTOR)::numeric, 2) as dist
 FROM small_world ORDER BY v <-> '[0,1,0]'::VECTOR LIMIT 7;
 
 -- Verify that index creation on a large vector produces an error
@@ -77,4 +77,4 @@ SELECT ARRAY[1,2,3] <-> ARRAY[3,2,1];
 
 -- Expect error due to mismatching vector dimensions
 SELECT 1 FROM small_world ORDER BY v <-> '[0,1,0,1]' LIMIT 1;
-SELECT vector_l2sq_dist('[1,1]'::vector, '[0,1,0]'::vector);
+SELECT l2sq_dist('[1,1]'::vector, '[0,1,0]'::vector);