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Merged
kofrezo merged 1 commit into from
Sep 21, 2026
Merged

db: faster ptr() as an inlinable SQL function #469

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46 changes: 15 additions & 31 deletions db/ptr.sql
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Original file line number Diff line number Diff line change
@@ -1,36 +1,20 @@
-- Reverse DNS name of an address. Plain SQL (no STRICT, no sub-SELECT, only
-- immutable functions) so Postgres inlines it into the calling query; it
-- expands the address from the inet_send() wire bytes (4 header bytes, then
-- the address), so the netmask is ignored. Kept in sync with
-- serveradmin_extras/serveradmin_powerdns/migrations/0006_ptr_function.py.
create or replace function public.ptr(intern_ip inet) returns text
immutable strict language plpgsql as $$
declare
ip_part text;
ip_text text;
ip_arr text[];
ip_filled boolean;
begin
if family(intern_ip) = 4 then
return (
select string_agg(part, '.' order by ord desc) || '.in-addr.arpa'
from regexp_split_to_table(host(intern_ip), '\.') with ordinality as s(part, ord)
);
language sql immutable parallel safe as $$
select case family(intern_ip)
when 4 then
get_byte(inet_send(intern_ip), 7)::text || '.' ||
get_byte(inet_send(intern_ip), 6)::text || '.' ||
get_byte(inet_send(intern_ip), 5)::text || '.' ||
get_byte(inet_send(intern_ip), 4)::text || '.in-addr.arpa'
else
ip_text := '';
ip_arr := regexp_split_to_array(host(intern_ip), ':');
ip_filled = false;

foreach ip_part in array ip_arr loop
if length(ip_part) = 0 and not ip_filled then
ip_text := ip_text || repeat('0', 32 - (array_length(ip_arr, 1) - 1) * 4);
ip_filled = true;
else
ip_text := ip_text || lpad(ip_part, 4, '0');
end if;
end loop;

return (
select string_agg(part[1], '.' order by ord desc) || '.ip6.arpa'
from regexp_matches(ip_text, '.', 'g') with ordinality as s(part, ord)
);
end if;
end;
regexp_replace(reverse(encode(substring(inet_send(intern_ip) from 5), 'hex')), '(.)', '\1.', 'g')
|| 'ip6.arpa'
end
$$;

create index concurrently server_ptr_idx on public.server(public.ptr(intern_ip) text_pattern_ops);
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