Postgres 9.6

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create table ipdesc (addr inet, category varchar(20));
insert into ipdesc (addr, category) values ('10.10.10.0/24', 'tens');
insert into ipdesc (addr, category) values ('20.20.20.0/24', 'twenties');
insert into ipdesc (addr, category) values ('50.50.50.0/24', 'fifties');
insert into ipdesc (addr, category) values ('50.50.50.0/30', 'sub-fifty');

create table test (ip inet);
insert into test values
  ('168.192.1.10'),
  ('10.10.10.20'),
  ('50.50.50.1'),
  ('50.50.50.10');

INSERT 0 4


create table mod_ipdesc
as select addr, category,
  inet(host(network(addr))) as amin,
  inet(host(broadcast(addr))) as amax
from ipdesc;

create index mod_ipdesc_addr on mod_ipdesc(amin, amax);

CREATE INDEX


select *
from test a
left outer join mod_ipdesc b
on (a.ip between b.amin and b.amax);


ip
addr
category
amin
amax


168.192.1.10
null
null
null
null

10.10.10.20
10.10.10.0/24
tens
10.10.10.0
10.10.10.255

50.50.50.1
50.50.50.0/24
fifties
50.50.50.0
50.50.50.255

50.50.50.1
50.50.50.0/30
sub-fifty
50.50.50.0
50.50.50.3

50.50.50.10
50.50.50.0/24
fifties
50.50.50.0
50.50.50.255



SELECT 5

ip	addr	category	amin	amax
168.192.1.10	null	null	null	null
10.10.10.20	10.10.10.0/24	tens	10.10.10.0	10.10.10.255
50.50.50.1	50.50.50.0/24	fifties	50.50.50.0	50.50.50.255
50.50.50.1	50.50.50.0/30	sub-fifty	50.50.50.0	50.50.50.3
50.50.50.10	50.50.50.0/24	fifties	50.50.50.0	50.50.50.255