add l1 distance to vec0 tables

tests/test-loadable.py

@@ -2247,6 +2247,48 @@ def test_vec0_stress_small_chunks():
         ]
     )
 
+def test_vec0_distance_metric():
+  base = "('[1, 2]'), ('[3, 4]'), ('[5, 6]')"
+  q = '[-1, -2]'
+
+  db = connect(EXT_PATH)
+  db.execute("create virtual table v1 using vec0( a float[2])")
+  db.execute(f"insert into v1(a) values {base}")
+
+  db.execute("create virtual table v2 using vec0( a float[2] distance_metric=l2)")
+  db.execute(f"insert into v2(a) values {base}")
+
+  db.execute("create virtual table v3 using vec0( a float[2] distance_metric=l1)")
+  db.execute(f"insert into v3(a) values {base}")
+
+  db.execute("create virtual table v4 using vec0( a float[2] distance_metric=cosine)")
+  db.execute(f"insert into v4(a) values {base}")
+
+  # default (L2)
+  assert execute_all(db, "select rowid, distance from v1 where a match ? and k = 3", [q]) == [
+      {"rowid": 1, "distance": 4.4721360206604},
+      {"rowid": 2, "distance": 7.211102485656738},
+      {"rowid": 3, "distance": 10.0},
+  ]
+
+  # l2
+  assert execute_all(db, "select rowid, distance from v2 where a match ? and k = 3", [q]) == [
+      {"rowid": 1, "distance": 4.4721360206604},
+      {"rowid": 2, "distance": 7.211102485656738},
+      {"rowid": 3, "distance": 10.0},
+  ]
+  # l1
+  assert execute_all(db, "select rowid, distance from v3 where a match ? and k = 3", [q]) == [
+      {"rowid": 1, "distance": 6},
+      {"rowid": 2, "distance": 10},
+      {"rowid": 3, "distance": 14},
+  ]
+  # consine
+  assert execute_all(db, "select rowid, distance from v4 where a match ? and k = 3", [q]) == [
+      {"rowid": 3, "distance": 1.9734171628952026},
+      {"rowid": 2, "distance": 1.9838699102401733},
+      {"rowid": 1, "distance": 2},
+  ]
 
 def rowids_value(buffer: bytearray) -> List[int]:
     assert (len(buffer) % 8) == 0