Puoi aggregare numeri fissi di righe usando row_number()
e aritmetica:
select min(date),
(array_agg(bid order by seqnum asc))[1] as open,
(array_agg(bid order by seqnum desc))[1] as close,
min(bid) as min_bid, max(bid) as max_bid
from (select t.*, row_number() over (order by date) as seqnum
from ticks t
) t
group by floor((seqnum - 1) / 500);
Questo usa "hack" per ottenere l'open
e close
-- usando gli array.