Insert if not exists for loadData/loadUpdateData

It would be great if it is possible to load only rows that don't exist yet, and not update existing rows like loadUpdateData does.

Example:

data.csv

or

So I want to be able to update csv file and load only newly added records but not overwrite existing.

In addition for some cases it might be useful to have other onDuplicateKey options:

• REPLACE = delete + insert

• WARN = show warning but proceed

Thanks.