I had to use a clob field to be mapped with hibernate 3. I was not working out of the box using the default type for mapping.

If we use String as mapping type, we could write to the Database, but cannot be read. No error, or exception of any kind, just the field set to null, which mean we loose the contents on update

Using Text type, make reading ok but writting impossible.

I found a lot of outdated, not answered question.

The problem seems to come from the Oracle driver, we were using a old Classe12.jar driver we replace it with the ojdbc14.jar and map the blog field to string and everything seems to work. :D