Select the next available IP address using Postgres inet and cidr types

select-next-ip.sql

SELECT sub.ip FROM
(SELECT set_masklen(((generate_series(1,
(2 ^ (32 - masklen('10.10.100.0/24'::cidr)))::integer - 2) +
'10.10.100.0/24'::cidr)::inet), 32) as ip) AS sub
WHERE sub.ip NOT IN
(SELECT ip_address from ip_table)
AND sub.ip > set_masklen('10.10.100.0/24', 32)+10
AND sub.ip < set_masklen(broadcast('10.10.100.0/24')::inet, 32)-5;