Postgres 14

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select version();

version

PostgreSQL 14.10 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-20), 64-bit

SELECT 1

create table parameters (
  name text,
  value int4range
);

insert into parameters values 
('Nominal power', int4range(1, 2, '[]')),
('Nominal power', int4range(2, 3, '[]')),
('Nominal power ratio', int4range(10, 15, '[]')),
('Nominal power ratio', int4range(17, 19, '[]')),
('Hydrogen production', int4range(1, 6, '[]')),
('Hydrogen production', int4range(2, 9, '[]'));

CREATE TABLE

INSERT 0 6

select name, 
       range_merge(range_agg(value)) as outer_range
  from parameters
 group by name
 order by outer_range;

name
outer_range

Nominal power
[1,4)

Hydrogen production
[1,10)

Nominal power ratio
[10,20)

SELECT 3

name	outer_range
Nominal power	[1,4)
Hydrogen production	[1,10)
Nominal power ratio	[10,20)