Multiple aggs,sums in 1 query

I have: create table tbl (a,b,c,d,e,f,g,h);

And i need to select in 1 query ,or the most performant way:

top 5(a)
top 5(b)
top 5(c): for each top5(c): top 5(d)
count(f) GROUP BY f

I can make these in separate queries but that means that postgresql would
read the table multiple-times?

Is it possible/doable/sane ?

Thanks