// Generate min. cost table for all pairs
INSERT into catchments
SELECT
    seq, id1 as source, id2 as target, cost
FROM
  pgr_apspWarshall('
    SELECT id, source, target, cost
    FROM network WHERE city = ''New York''', false, false);

// Select max(min(distance))
SELECT source, max(cost) as maxcost
FROM catchments
WHERE cost <= 10 **km** GROUP BY source ORDER BY maxcost ASC;