Re: Comparing first 3 numbers of a IPv4 address?

Hello,

I'm trying to program a PHP-script, where users
can rate the "goodness" of the other players:

       create table pref_rep (
               id varchar(32) references pref_users(id) check (id <> author),
               author varchar(32) references pref_users(id),
               author_ip inet,
               good boolean,
               last_rated timestamp default current_timestamp
       );

To (try to) prevent tampering I'd like to delete
entries for the same id coming
from the same IP in the course of last hour:

       create or replace function pref_update_rep(_id varchar,
               _author varchar, _author_ip inet,
               _good boolean) returns void as $BODY$
               begin

               delete from pref_rep
               where id = _id and
               author_ip = _author_ip and
               age(to_timestamp(last_rated)) < interval '1 hour';

               update pref_rep set
                   author    = _author,
                   author_ip = _author_ip,
                   good      = _good,
                   last_rated = current_timestamp
               where id = _id and author = _author;

               if not found then
                       insert into pref_rep(id, author, author_ip, good)
                       values (_id, _author, _author_ip, _good);
               end if;
               end;
       $BODY$ language plpgsql;

I have 2 questions please:

1) if I'd like to compare just the first 3 numbers of
the IP address instead of the 4, how can I do it?
(yes, I know about the A,B,C type of IPv4 networks...)

2) Do I need to add an index to my table
or are id and author indexed already?

Thank you!
Alex

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