Nice :-))))

1. First paragraph: tested, went OK.
2. Second paragraph: tested, ping server: Average round trip: 10 ms - conclusion: went OK.
3. My opinion at third paragraph: if an elegant approach isn't possible, I have two ways: migrate to an SQL server or splitting the big table in a small parts - nobody will see this...

Thanks a lot for your help, but I'm still open to other ideas...