message: test_uuid.test: test UUID v4.1 conformance
diff: @@ -42,3 +42,19 @@ SELECT * FROM uuids ORDER BY gen_random_uuid()
  # we can select gen_random_uuid
  statement ok
  SELECT gen_random_uuid() FROM uuids
  +
  +# UUID v4 follows `XXXXXXXX-XXXX-4XXX-XXXX-XXXXXXXXXXXX` format
  +query I
  +SELECT DISTINCT substring(uuid()::varchar, 15, 1) FROM range(100)
  +----
  +4
  +
  +# UUID v4 variant 1 follows `XXXXXXXX-XXXX-4XXX-[89ab]XXX-XXXXXXXXXXXX` format
  +# the probability for 100 iters not to cover the 4 possible values is (3/4)**100 == 3e-13
  +query I
  +SELECT DISTINCT substring(uuid()::varchar, 20, 1) AS x FROM range(100) ORDER BY x
  +----
  +8
  +9
  +a
  +b
  