in the meantime i figured out how to solve the problem. for everyone who is interested here my solution:
there are two possible solutions. first hibernate deleted my tables, to avoid that include
in the persistence.xml.
an other way is to specifiy the table in the column entity annotation:
@Column(name="image", columnDefinition="MEDIUMBLOB NOT NULL")
i just tested the first solution, since the second is databse dependend.
have a nice day..