Database limit(s)

Hi there, I'ld like to ask, is there any hard or soft limit in database? I mean, how many object canbe stored in the DB? Or how many children object could under a parent? I've read the docs about the limits ( http://www.openldap.org/doc/admin24/limits.html), but there are only the sizelimit and timelimit (which aren't affected me now). In other words, which parameters do I check before I start to design a database (LDAP/non-LDAP (eg. OS) parameters)? Thanks, a.