DB sessions store table structure

Hello,

I was working on a POC (proof of concept) to prove that RAILS is an
alternative to consider for our web projects. I have enjoyed my RAILS
experience till now. I was trying to create a sessions table in Oracle
since I cannot create it through the migration script as it has been
ruled out by the Database team. What is the column type for the “data”
column in the sessions table? Would it be varchar2 or CLOB? If it is
varchar2 what would the total size that has to be allocated? Any help
would be appreciated.

Thanks in advance