WITH RECURSIVE
range AS (
  SELECT min(id) AS min, max(id) AS max FROM table1
), 
r AS (
    SELECT array[]::integer[] AS res
  UNION ALL
    SELECT CASE WHEN (id IS NULL) THEN res ELSE res||id END 
    FROM (SELECT (min + (max - min) * random())::int AS rnd,res FROM r JOIN range ON true) AS _r
    LEFT JOIN table1 ON id=rnd AND id <> all(res) 
    WHERE 
      id IS NULL OR coalesce(array_length(res,1),0)<=10 
) 
SELECT unnest(res) FROM (
  SELECT res FROM r ORDER BY array_length(res,1) DESC NULLS LAST LIMIT 1
) AS t;

WITH RECURSIVE
r AS (
    SELECT array[]::integer[] AS res,min(id) AS min, max(id)-min(id) AS range, 0 as cnt FROM table1
  UNION ALL
    SELECT CASE WHEN id IS NULL THEN res ELSE res||id END, min, range, CASE WHEN id IS NULL THEN cnt ELSE cnt+1 END
    FROM (SELECT (min + range * random())::int AS _id, * FROM r) AS tmp
    LEFT JOIN table1 ON id=_id AND NOT id=ANY(res)
    WHERE
      cnt<10
)
SELECT unnest(res) FROM (
  SELECT res FROM r ORDER BY cnt DESC NULLS LAST LIMIT 1
) AS t;

range AS (
  SELECT min(id) AS min, max(id) AS max FROM table1
), 

WITH RECURSIVE
r AS (
    SELECT array[]::integer[] AS res,min(id) AS min, max(id)-min(id) AS range FROM table1
  UNION ALL
    SELECT res||ARRAY(SELECT id FROM table1 WHERE id IN (SELECT (min+range*random())::int FROM generate_series(1,1000)) AND NOT id=ANY(res)), min, range
    FROM r
    WHERE
      coalesce(array_length(res,1),0)<1000
)
SELECT unnest(res) FROM (
  SELECT res FROM r ORDER BY array_length(res,1) DESC NULLS LAST LIMIT 1
) AS t LIMIT 1000;

WITH RECURSIVE
r AS (
    SELECT array[]::integer[] AS res,min(id) AS min, max(id)-min(id) AS range FROM table1
  UNION ALL
    SELECT res||ARRAY(SELECT id FROM table1 WHERE id=(SELECT (min+range*random())::int) AND NOT id=ANY(res)), min, range
    FROM r WHERE coalesce(array_length(res,1),0)<10
)
SELECT unnest(res) FROM (
  SELECT res FROM r ORDER BY array_length(res,1) DESC NULLS LAST LIMIT 1
) AS t;