Grouping rows by value until it changes (grouping includes the first changed value)

Question

I have the following dataset:

The rows are sorted in ascending order by the start_time field, and I want to group rows that have a sequence of false values, until the first true value, including the first true value.

That is, for the above dataset I want the following output:

(the grouping field can include other values than what I wrote)

Answer 1

I think a window sum can do what you want:

select t.*, 
    1 + coalesce(sum(case when bool = true then 1 else 0 end) over(
            order by start_time
            rows between unbounded preceding and 1 preceding
        ), 0) as grp
from mytable t