Having table

data ratio
a 0.3
b 0.5
c 0.4
d 1.0

need to get the table where each element appears 1/ratio times

value
a
a
a
a
b
b
c
c
c
d

let’s create the table

create table public.log
(
    data  text,
    ratio double precision
);
INSERT INTO public.log (data, ratio) VALUES ('a', 0.3);
INSERT INTO public.log (data, ratio) VALUES ('b', 0.5);
INSERT INTO public.log (data, ratio) VALUES ('c', 0.4);
INSERT INTO public.log (data, ratio) VALUES ('d', 1);

select data, ratio from log;

output:

value ratio
a 0.3
b 0.5
c 0.4
d 1.0 
select data, ceil(1/ratio) from log;

output:

value ceil
a 4
b 2
c 3
d 1

let’s explore series function

SELECT generate_series(1, ceil(1/.2)::integer);

output:

value
1
2
3
4
5

let’s combine

select data
  from log
  join generate_series(1, ceil(1/ratio)::integer) as series on true;

output:

value
a
a
a
a
b
b
c
c
c
d

let’s explore array function

SELECT array_fill(0, ARRAY[5]);

output:

value
{0,0,0,0,0}

let’s explore unnest function

SELECT unnest(array_fill(0, ARRAY[5]));

output:

value
0
0
0
0
0

let’s combine

select l.data
  from log l
  join unnest(array_fill(0, ARRAY[ceil(1/l.ratio)::integer])) on true;

output:

value
a
a
a
a
b
b
c
c
c
d

What we see, that SQL has a bunch of interesting functions to work with data