This post is not about solving some problem. Sadly I don't know hot to solve following problem. There are just work arounds.
I have following configuration:
MySQL: 5.5.27
hibernate dialect: org.hibernate.dialect.MySQLInnoDBDialect
hibernate: 3.6.9
In my model I have entity with following attribute:
@Entity
@Table(name = "site")
public class Site extends AbstractEntity {
...
@Column(unique = true, nullable = true, length = 1024 * 100)
private String description;
...
}
When I run program follow error appears in logs and table site is not created.
2013-06-01 12:15:24 [main] ERROR org.hibernate.tool.hbm2ddl.SchemaUpdate -
Unsuccessful: create table site (id_site integer not null auto_increment, description longtext unique, name varchar(250) unique, url_pattern longtext not null unique, id_image integer, primary key (id_site)) ENGINE=InnoDB
2013-06-01 12:15:24 [main] ERROR org.hibernate.tool.hbm2ddl.SchemaUpdate -
BLOB/TEXT column 'description' used in key specification without a key length
Problem is that column 'description' is marked as unique. In InnoDB maximum length of key could be just 767 characters for a single-byte charset like LATIN1 and only 255 characters for UTF8.
Look at possible workarounds:
- avoid indexes, don't use unique = true
- make column length smaller (255) characters for UTF8
- compute hash from long column store in in another column and create index on hash column
If you'll have some other possible solution than please let me know.
