To be honest, I wouldn't do this in perl. I would do this in the database. You could probably federate the bunch of them and do some sort of SELECT COUNT(*) FROM T1 WHERE PRIMKEY NOT IN (SELECT PRIMKEY FROM T2, T3, T4, T5, T6, T7) or something. But that's probably not really fast either.

Instead, invest in replication technology if your vendor doesn't come with any by default. (I know DB2 has replication technology, but I think it's an add-on cost.) And get that vendor to show you how to be convinced that everything is synchronised. If you're doing this for high-availability (doesn't sound like it - 6 fail-over servers seems a bit high), then invest in HA data replication (HADR) and set it up - and, again, ask your vendor to prove it's working (or at least to show you how to prove it's working).

I'm sure you could do this in perl. But I wouldn't. And I use perl for almost everything - just ask my teammates.