How to rank event times by a given time window using SQL?

Question

I am struggling to find a way to rank the events using SQL. The goal is to increment the rank whenever an event occurred more than delta seconds (e.g. 1 second) from the previous observation. So far my attempt is shown below:

select a.event_time, a.user_name, a.object_name, a.rnk, case when a.ddif <= 1000 then 0 else 1 end as new_query,
            case when a.ddif <= 1000 then 0 else rnk end as new_rnk
from (
    select *, rank() OVER (PARTITION BY user_name ORDER BY event_time) AS rnk,
              date_diff('second',lag(event_time) OVER (PARTITION BY user_name ORDER BY event_time),event_time) as ddif
    from tmp
    ) a

But it gives me just the following results and I still don't know how to achieve the results in yellow (either of them works for me perfectly).

I'd appreciate any help with that.

Please note: I am using Presto DB, hence I am limited to this query engine.

Answer 1

Thanks for all the good tips that pointed me the direction to the final solution which is:

select a.*, sum (case when a.ddif <= 1 then 0 else 1 end) over (partition by user_name order by event_time) as acc_rnk
    from (
        select *, date_diff('second',lag(event_time) OVER (PARTITION BY user_name ORDER BY event_time),event_time) as ddif
        from tmp
        ) a