Originally posted by Mr.Hanky

COMMIT=Y

With your buffer at 4 million bytes you will be commiting every 4 megs (roughly). This is better than the oracle default which is to try and import the entire table before a commit. You will also run the risk of blowing out your rollback segs, or tablespace if it is too small.
Of course, you realize Mr.H is taking about import here and not export.

And, if we check the docs ( http://technet.oracle.com/docs/produ...ch01.htm#46045 ) we notice that BUFFER does not apply for DIRECT export.