Optimize groupwise maximum query

Question

select * 
from records 
where id in ( select max(id) from records group by option_id )

This query works fine even on millions of rows. However as y

Answer 1

select distinct on (option_id) *
from records
order by option_id, id desc

Indexes will only be used if the cardinality is favorable. That said you can try a composite index

create index index_name on records(option_id, id desc)