Snowflake table and generator functions does not give expected result - sql

Question

I tried to create a simple SQL to track query_history usage, but got into trouble when creating my timeslots using the table and generator functions (the CTE named x below).
I got no results at all when limiting the query_history using my timeslots, so after a while I hardcoded an SQL to give the same result (the CTE named y below) and this works fine.
Why does not x work? As far as I can see x and y produce identical result?
To test the example first run the code as it is, this produces no result.
Then comment the line x as timeslots and un-comment the line y as timeslots, this will give the desired result.
with
x as (
select
dateadd('min',seq4()*10,dateadd('min',-60,current_timestamp())) f,
dateadd('min',(seq4()+1)*10,dateadd('min',-60,current_timestamp())) t
from table(generator(rowcount => 6))
),
y as (
select
dateadd('min',n*10,dateadd('min',-60,current_timestamp())) f,
dateadd('min',(n+1)*10,dateadd('min',-60,current_timestamp())) t
from (select 0 n union all select 1 n union all select 2 union all select 3
union all select 4 union all select 5)
)
--select * from x;
--select * from y;
select distinct
user_name,
timeslots.f
from snowflake.account_usage.query_history,
x as timeslots
--y as timeslots
where start_time >= timeslots.f
and start_time < timeslots.t
order by timeslots.f desc;
(I know the code is not optimal, this is only meant to illustrate the problem)

Answer 1

SEQ:
Returns a sequence of monotonically increasing integers, with wrap-around. Wrap-around occurs after the largest representable integer of the integer width (1, 2, 4, or 8 byte).
If a fully ordered, gap-free sequence is required, consider using the ROW_NUMBER window function.
For:
with x as (
select
dateadd('min',seq4()*10,dateadd('min',-60,current_timestamp())) f,
dateadd('min',(seq4()+1)*10,dateadd('min',-60,current_timestamp())) t
from table(generator(rowcount => 6))
)
SELECT * FROM x;
Should be:
with x as (
select
(ROW_NUMBER() OVER(ORDER BY seq4())) - 1 AS n,
dateadd('min',n*10,dateadd('min',-60,current_timestamp())) f,
dateadd('min',(n+1)*10,dateadd('min',-60,current_timestamp())) t
from table(generator(rowcount => 6))
)
SELECT * FROM x;