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Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Entities/Ids/SequenceGenerator"
< EclipseLink | UserGuide | JPA | Basic JPA Development
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m (Fixed annotation @GeneratedValue. Was @GeneratorValue) |
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=@SequenceGenerator= | =@SequenceGenerator= | ||
| − | If you use the [[EclipseLink/UserGuide/JPA/Basic JPA Development/Entities/Ids/GeneratedValue|@GeneratedValue]] annotation to specify a primary key generator of type <tt>SEQUENCE</tt>, then you can use the <tt>@SequenceGenerator</tt> annotation to fine-tune this primary key generator to do the following: | + | If you use the [[EclipseLink/UserGuide/JPA/Basic JPA Development/Entities/Ids/GeneratedValue|<code>@GeneratedValue</code>]] annotation to specify a primary key generator of type <tt>SEQUENCE</tt>, then you can use the <tt>@SequenceGenerator</tt> annotation to fine-tune this primary key generator to do the following: |
* change the allocation size to match your application requirements or database performance parameters; (this should match your database sequence <code>INCREMENT</code>) | * change the allocation size to match your application requirements or database performance parameters; (this should match your database sequence <code>INCREMENT</code>) | ||
* change the initial value to match an existing data model (for example, if you are building on an existing data set for which a range of | * change the initial value to match an existing data model (for example, if you are building on an existing data set for which a range of | ||
| Line 52: | Line 52: | ||
@Id | @Id | ||
@SequenceGenerator(name="Emp_Seq", allocationSize=25) | @SequenceGenerator(name="Emp_Seq", allocationSize=25) | ||
| − | @ | + | @GeneratedValue(strategy=SEQUENCE, generator="Emp_Seq") |
@Column(name="EMP_ID") | @Column(name="EMP_ID") | ||
public Long getId() { | public Long getId() { | ||
| Line 67: | Line 67: | ||
<attributes> | <attributes> | ||
<id name="id"> | <id name="id"> | ||
| + | <column name="EMP_ID"/> | ||
<generated-value generator="Emp_Seq" strategy="SEQUENCE"/> | <generated-value generator="Emp_Seq" strategy="SEQUENCE"/> | ||
<sequence-generator name="Emp_Seq" allocationSize="25"/> | <sequence-generator name="Emp_Seq" allocationSize="25"/> | ||
| − | |||
</id> | </id> | ||
... | ... | ||
| Line 80: | Line 80: | ||
{{EclipseLink_JPA | {{EclipseLink_JPA | ||
|previous=[[EclipseLink/UserGuide/JPA/Basic_JPA_Development/Entities/Ids/TableGenerator|@TableGenerator]] | |previous=[[EclipseLink/UserGuide/JPA/Basic_JPA_Development/Entities/Ids/TableGenerator|@TableGenerator]] | ||
| − | |next= [[EclipseLink/UserGuide/JPA/Basic JPA Development/ | + | |next= [[EclipseLink/UserGuide/JPA/Basic JPA Development/Entities/Ids/UuidGenerator|@UuidGenerator]] |
|up= [[EclipseLink/UserGuide/JPA/Basic JPA Development/Entities/Creating_and_Configuring_Entities|Configuring Entities]] | |up= [[EclipseLink/UserGuide/JPA/Basic JPA Development/Entities/Creating_and_Configuring_Entities|Configuring Entities]] | ||
|version=2.2.0 DRAFT}} | |version=2.2.0 DRAFT}} | ||
Latest revision as of 11:41, 21 November 2017
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Key API
@SequenceGenerator
If you use the @GeneratedValue annotation to specify a primary key generator of type SEQUENCE, then you can use the @SequenceGenerator annotation to fine-tune this primary key generator to do the following:
- change the allocation size to match your application requirements or database performance parameters; (this should match your database sequence
INCREMENT) - change the initial value to match an existing data model (for example, if you are building on an existing data set for which a range of
| Attribute | Description | Default | Required? |
|---|---|---|---|
| name | The name of the generator must match the name of a GeneratedValue with its strategy attribute set to SEQUENCE. | Yes | |
| allocationSize | An int value that must match the increment size of the database sequence object. | 50 | No |
| initialValue | An int value to start all primary keys. | 0 | No |
| sequenceName | A String name of the sequence | SequenceGenerator.name | No |
The following example shows how to use this annotation to specify the allocation size for the SEQUENCE primary key generator named Emp_Seq.
Example: @SequenceGenerator
@Entity public class Employee implements Serializable { ... @Id @SequenceGenerator(name="Emp_Seq", allocationSize=25) @GeneratedValue(strategy=SEQUENCE, generator="Emp_Seq") @Column(name="EMP_ID") public Long getId() { return id; } ... }
Example: Using <sequence-generator>
<entity class="Employee"> <attributes> <id name="id"> <column name="EMP_ID"/> <generated-value generator="Emp_Seq" strategy="SEQUENCE"/> <sequence-generator name="Emp_Seq" allocationSize="25"/> </id> ... </attributes> </entity>
