User Action Cohorts

Hi Everyone,

I'm looking for way to query user action cohorts.
I went through this solution https://yute.com/post/cohorts-clickhouse/ but it's not good for me.
They are using JOIN between the ActionX and ActionY.
It might work for Account level, but for a specific user, when you got millions of users(and more) the join will just kill the memory.

I could achieve this using the retention function, but only one line at a time.
Doing this for 3 months is a waste of cpu and time.

Is there any other option into doing such query in one time for the entire cohort table?

The scheme is generic: UserId, EventTime, Action
I want to calculate a cohort between 2 dates and 2 different action.

Any idea/solution is welcome.

Thanks.