I was working today and trying to load some data from a new vendor. Several of the columns were declared as varchar2(4000) yet when sqlldr ran I was seeing the error "field in datafile exceeds maximum length". My first thought was that I may have a filed with more than 4000 characters. But, after examining one of the problem data lines I knew that was not the case. After a quick search I found that sqlldr defaults string lengths to 255 character unless specified otherwise in the control file. I had come across this before but had forgotten since the vast majority of data that I deal with doesn't run into this restriction. To resolve the issue I declared the long string columns as CHAR(4000) in the control file.