test use less memory, pass on 2GB ram machine (#2730)
test use less memory, pass on 2GB ram machine (#2730)


jangorecki/data.table,Rdatatable/data.table,jangorecki/data.table,jangorecki/data.table,vlulla/data.table,Rdatatable/data.table,jangorecki/data.table,vlulla/data.table,Rdatatable/data.table,Rdatatable/data.table,vlulla/data.table,vlulla/data.table