In oracle 9i for raw logs which oracle datatype is preferable.
I am thinking of blob or clob as it offers the flexible space in database.
But what about the performance because large no of logs generation.
For log generation, IMHO, definitely go for a varchar2 type. As you said, LOBs would be slower, but mainly they are inappropriate : one log will never ever be longer than 4000 bytes, it will be much smaller. Consider a Varchar2(500), at most a Varchar2(1000), not bigger (unless you are logging in japanese using UTF8, having all characters 3-bytes long ).
BTW, have you given up OCCI ? If you have any question, I'll be glad to help if I can, just open a new thread.