Using Hibernate UUIDGenerator via annotations

Question

I\'m using my uuid as following:

@Id
@GeneratedValue(generator = \"uuid\")
@GenericGenerator(name = \"uuid\", strategy = \"uuid\")
@Column(name = \"uuid\", u         


        

Answer 1

Unknown Id.generator: hibernate-uuid

@Id
@GeneratedValue(generator = "uuid")
@GenericGenerator(name = "uuid", strategy = "org.hibernate.id.UUIDGenerator")
@Column(name = "id", unique = true)
public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

Answer 2

As @natan pointed out in a comment, if you are using Hibernate 5 the below code is sufficient:

@Id 
@GeneratedValue
private java.util.UUID id;

Define the id column with the type of BINARY(16) in MySQL or it's equivalent in other SQL implementations.

Answer 3

It should be uuid2:

...
@GenericGenerator(name = "uuid", strategy = "uuid2")
...

See 5.1.2.2.1. Various additional generators.

Answer 4

This will use UUID v4 and the auto generated uuid will be stored in the column as usual varchar(36):

@Id
@GeneratedValue(generator = "uuid2")
@GenericGenerator(name = "uuid2", strategy = "uuid2")
@Column(length = 36)
private String uuid;

This should have some performance impact:

• consumed size is more than BINARY(16)
• after hydration the java.lang.String instance consumes more memory than java.util.UUID: 112 bytes for UUID as string versus 32 bytes (i.e. two longs + obj header) for UUID.

But it's much more easier to work with string'ed UUID - easier to write queries and you can see the contents of the table.

Tested on Hibernate 5.3

Answer 5

HibernateDoc says you can use following:

@Id
@GeneratedValue(generator="system-uuid")
@GenericGenerator(name="system-uuid", strategy = "uuid")
@Column(name = "uuid", unique = true)
private String uuid;

I hope you are using Hibernate 3.5.

Answer 6

Try...

@Id
@GeneratedValue(generator = "uuid2")
@GenericGenerator(name = "uuid2", strategy = "uuid2")
@Column(name = "uuid", columnDefinition = "BINARY(16)")
public UUID getId()
{
    return id;
}

public void setId(UUID i)
{
    id = i;
}

Note the "uuid2" as opposed to "uuid".