MariaDB 10.3

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CREATE TABLE myTable (`id` INTEGER, `col1` INTEGER, `col2` INTEGER);

INSERT INTO myTable (`id`, `col1`, `col2`) VALUES
  ('1', '12345', '6789'),
  ('2', '6789', '12345'),
  ('3', '3333', '4213'),
  ('4', '12345', '6789'),
  ('5', '6789', '12345'),
  ('6', '1111', '2222'),
  ('7', '12345', '6789');

Records: 7  Duplicates: 0  Warnings: 0


SELECT *
FROM myTable
WHERE (LEAST(col1, col2), GREATEST(col1, col2)) IN (
  SELECT LEAST(col1, col2) c1, GREATEST(col1, col2) c2
  FROM myTable
  GROUP BY c1, c2
  HAVING COUNT(*) >= 4 and COUNT(*) <= 100000
);


id
col1
col2


1
12345
6789

2
6789
12345

4
12345
6789

5
6789
12345

7
12345
6789


SELECT t1.*
FROM myTable t1 
INNER JOIN (
  SELECT LEAST(col1, col2) c1, GREATEST(col1, col2) c2
  FROM myTable
  GROUP BY c1, c2
  HAVING COUNT(*) >= 4 and COUNT(*) <= 100000
) t2 ON (t2.c1, t2.c2) = (LEAST(col1, col2), GREATEST(col1, col2));


id
col1
col2


1
12345
6789

2
6789
12345

4
12345
6789

5
6789
12345

7
12345
6789