Hibernate无法创建表hibernate_sequences

Question

Hibernate version:

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-core</artifactId>
    <version>5.2.4.Final</version>
</dependency>

ExportDB.java :

public class ExportDB {
    public static void main(String[] args) {
        ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
        Metadata metadata = new MetadataSources(serviceRegistry).buildMetadata();
        SchemaExport schemaExport = new SchemaExport();
        schemaExport.create(EnumSet.of(TargetType.DATABASE), metadata);
    }
}

Run ExportDB.java :

2016-11-19 00:22:12,845 WARN [org.hibernate.orm.connections.pooling] - HHH10001002: Using Hibernate built-in connection pool (not for production use!)
Hibernate: drop table if exists hibernate_sequences
Hibernate: drop table if exists user
Hibernate: create table hibernate_sequences (sequence_name varchar(255) not null, sequence_next_hi_value bigint, primary key (sequence_name))
Hibernate: create table user (id bigint not null, balance decimal(20,4) default 0.00, createTime time, displayName varchar(64), password varchar(64), username varchar(64), primary key (id))
Hibernate: alter table user add constraint UK_7kuje5s4lbyq9qyv1r9ecm2it unique (username)

Database:

MariaDB [cms]> show tables;
+----------------+
| Tables_in_cms |
+----------------+
| investor       |
+----------------+
1 row in set (0.00 sec)

When I use printed SQL to create hibernate_sequences :

MariaDB [cms]> create table hibernate_sequences (sequence_name varchar(255) not null, next_val bigint, primary key (sequence_name));
ERROR 1071 (42000): Specified key was too long; max key length is 767 bytes

How can I make ExportDB.java can create hibernate_sequences ?

Answer 1

You are using utf8mb4 , correct? And you are using 5.6 or older?

Plan A: Upgrade to 5.7.

Plan B: Decrease 255 to 191 or less. (Did you really need 255??)

Plan C: Change to CHARACTER SET utf8 (assuming you don't need Emoji or Chinese)

Plan D: Normally a 'sequence' is something numeric. If that is the case, won't INT UNSIGNED or BIGINT UNSIGNED work?

Answer 2

It is due to the utf8mb4 charset on the column definition in my case.

Too long varchar column cannot be used in primary_key.

So we can manually create the table and make it correct.

The following create table query do the trick.

create table hibernate_sequences (
   sequence_name varchar(255) CHARACTER SET utf8 not null ,
    next_val bigint,
    primary key (sequence_name)
) engine=MyISAM