messing around with sequences in postgres

sequences.sql

drop table if exists seq_test;
create table seq_test as

with

dates as (
    select
    0 as id,
    generate_series(
        '2017-01-01'::date,
        '2017-01-07'::date,
        '1 day'::interval)::date as date
),

sequences as (
    select
        *,
        row_number() over w as sequence
    from
        dates
    window w as (
        partition by id
        order by date
    )
),

vals as (
    select
        *,
        first_value(sequence) over w as first_seq,
        last_value(sequence) over w as last_seq
    from
        sequences
    window w as (
        partition by id
        order by date
        rows between unbounded preceding and unbounded following
    )
)

select
    *,
    case
        when sequence = last_seq then true
        else false
        end as is_latest_sequence
from
    vals
;