Thanks for the reference. Why don't you keep your data in a DB? I load almost anything that isn't a small atomic data frame into a RDBMS.

BTW one thing that always made me avoid DT (I even preferred sqldf before dplyr was created) was its IMHO weird syntax. I always found the syntax of (d)plyr much more convenient. ATM it seems to me that dplyr has won the contest of alternative data management libraries. I cannot remember when I last read a blog post, article, or book that preferred DT over dplyr. I'm old enough to have learned that wrt libraries, it's wise to follow the crowd.