Hibernate Temporal.TIMESTAMP maps to mysql datetime without millis

streetturtle :

I have an entity with a field defined following way:

@Temporal(TemporalType.TIMESTAMP)
@Column(name = "some_datetime")
private java.util.Date someDateTime;

I would assume that Hibernate would create a table with corresponding column of type DATETIME(3) (for MySQL), however the table's column is just a DATETIME, so when I store a Date with milliseconds they are lost:

describe some_table;
+---------------+--------------+------+-----+---------+-------+
| Field         | Type         | Null | Key | Default | Extra |
+---------------+--------------+------+-----+---------+-------+
| ...           | ...          | NO   | PRI | NULL    |       |
| some_datetime | datetime     | YES  |     | NULL    |       |
| ...           | ...          | NO   |     | NULL    |       |
+---------------+--------------+------+-----+---------+-------+

I guess I need to add a columnDefinition parameter to the @Column annotation, but why it's not done automatically by Hibernate, as I explicitly told that I want to have a TIMESTAMP supported by the table.

I tried the above with:
- 10.1.14 - MariaDB
- 5.7.29 - MySQL

Hibernate version is 5.2.18.Final with MySQL5InnoDBDialect

SternK :

I would suggest you to use org.hibernate.dialect.MySQL57Dialect dialect instead of org.hibernate.dialect.MySQL5InnoDBDialect.

As I see, the Types.TIMESTAMP type redefine here as datetime(6)

public class MySQL57Dialect extends MySQL55Dialect {
  public MySQL57Dialect() {
    super();
    registerColumnType( Types.TIMESTAMP, "datetime(6)" );
    // ...
  }
}

but MySQL5InnoDBDialect extends MySQL5Dialect that extends MySQLDialect where Types.TIMESTAMP declared as


public class MySQLDialect extends Dialect {
  public MySQLDialect() {
    // ..
    registerColumnType( Types.TIMESTAMP, "datetime" );
  }
}

And, by the way, this dialect is marked as deprecated:

/** A Dialect for MySQL 5 using InnoDB engine
 *  ...
 * @deprecated Use "hibernate.dialect.storage_engine=innodb" environment variable or JVM system property instead.
 */
@Deprecated
public class MySQL5InnoDBDialect extends MySQL5Dialect {
   // ...
}