Postgres 16

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create table ranges (range int8range);

CREATE TABLE

insert into ranges (range) values
  ('[1,8)'), ('[2,6)'),
  ('[10,20)'), ('[15,30)'),
  ('[35,40)'), ('[40,50)'),
  ('[50,60)'), ('[60,70)')

INSERT 0 8

SELECT unnest(ra.mr)
FROM (
    SELECT range_agg(range) AS mr FROM ranges
) AS ra

unnest

[1,8)

[10,30)

[35,70)

SELECT 3