> I would like to limit the size of my firebird db. Is it possible?

When the amount of data hold in DB is limited the file should not grow
infinitely.

> Obviuosly I periodically delete record in table to save space, but
> the only way I found to decrease db size is to export and import it
> through gbak. I would like to do it without disconnect my application
> to db?

It should not be necessary to shrink database since free space inside
database is recycled once the entire page contains deleted data only and
the corresponding transactions are finished.

Periodically deleting records shold be sufficient in your situation.

Elmar