While not related to your file size question, you may want to use the perl module
BerkeleyDB rather than
DB_File since it can take advantage of much more of Berkeley DB features. Also, BTW the anonymonk's comment that Berkeley DB is not a server is wrong - of course Berkeley DB is a server. Perhaps what he/she meant is that there is no SQL front end to that server, but there again he/she is also now wrong - the
DBI distribution comes with
DBD::DBM which provides a DBI/SQL front end to Berkeley DB using either of the perl modules (
BerkeleyDB or
DB_File).
DBD::DBM's SQL is limited, but it can do INNER and OUTER joins on two tables so minimally qualifies as an RDBMS.