The SQL Generated code is great for most of my tables, but some of the columns have very large text strings. The generation is creating them as varchar(16000000) which is well beyond the maximum for a db2 varchar.

Is there a way to tell hibernate to have the create script use a blob whenever it encounters a string too large for db2 varchar's to handle? For the mySQL generation, the sql code correctly converts large strings to the correct type.

Implement your own Dialect. Check the constructor of the exiting DB2Dialect and MySQLDialect on how to register the types to use.