The OP seems a bit unwilling to listen, but if you truncate the hash, you meet his spec.

use Digest::MD5 qw/ md5_hex /;

my $digest=md5_hex("http://www.berghold.net");
printf "%d\n", hex(substr($digest, -4)) % 10_000;
[download]

So the one-liner he's looking for would be hex(substr(md5_hex($someurl), -4)) % 10_000. I'm betting that is somewhat collision resistant. The OP still should consider enlarging his int2 column to int4 or int8 or even char(4)