Maximum number of rows in an external table

Hi - can anyone tell me what the maximum number of rows which can be accessed in an external table is, please? I see (from note 336186.1) that the maximum number of rows in a database table is unlimited, and that the maximum size of an external file is o/s dependent (in this case the o/s is Solaris). The reason for this question is that at the weekend we hit the SQL*Ldr limit of 4,294,967,295 (I believe this is a 'hard' limit which cannot be increased - is this true?) and, whilst we could split the SQL*Ldr file into 2 or more files I wonder whether we would be better advised to define the file as an external table, and read the rows into the database