Hi, I had this error too and it's generated when knowage tries to create a new table in your write-default database connection (write-default datasource) to act as a cache for datasets in cockpit.
The problem seams to be with the hibernate.cfg.xml located at <KNOWAGE-SERVER_CE>/webapps/knowagecockpitengine/WEB-INF/classes. It is defined to use MySQL and if you are using another DBMS you'll have to change the hibernate dialect according to your database Manager.
Another issue that i've found and related to this problem of generating knowage cache: when you show a parameter as one of your columns (ex.: Select Col1, $P{myParameter} from my_table where col2 = $P{myParameter}), you have to cast its size ( in my example: ex.: Select Col1, $P{myParameter} :: varchar(50) from my_table where col2 = $P{myParameter} or (at least in my case: PostgreSQL) Knowage will try to create a column for it using VARCHAR (2147483647) which is too large for a Varchar in PostgreSQL and raises an error.
Tell me if you've got your problem solved.
Cheers
