@OptimisticLocking

Use @OptimisticLocking to specify the type of optimistic locking EclipseLink should use when updating or deleting entities.

Annotation Elements

Table 2-45 describes this annotation's elements.

Table 2-45 @OptimisticLocking Annotation Elements

Annotation Element Description Default

Annotation Element	Description	Default
`cascade`	(Optional) Specify where the optimistic locking policy should cascade lock. When changing private owned and delete orphan object, EclipseLink will update the version. Currently only supported with `VERSION_COLUMN` locking.	`false`
`selectedColumns`	(Optional) Specify a list of columns that will be optimistically locked. This element is required when `type=SELECTED_COLUMNS`.
`type`	(Optional) The type of optimistic locking policy to use: `ALL_COLUMNS` – EclipseLink compares every field in the table with the `WHERE` clause, when performing and update or delete operation. `CHANGED_COLUMNS` – EclipseLink compares only the changed fields in the `WHERE` clause when performing an update. `SELECTED_COLUMNS` – EclipseLink compares the selected field in the `WHERE` clause when performing and update or delete operation on the `SelectedColumns`. `VERSION_COLUMN` – EclipseLink compares a single version number in the `WHERE` clause when performing an update.	`VERSION_COLUMN`

cascade

(Optional) Specify where the optimistic locking policy should cascade lock. When changing private owned and delete orphan object, EclipseLink will update the version.

Currently only supported with VERSION_COLUMN locking.

false

selectedColumns

(Optional) Specify a list of columns that will be optimistically locked.

This element is required when type=SELECTED_COLUMNS.

type

(Optional) The type of optimistic locking policy to use:

ALL_COLUMNS – EclipseLink compares every field in the table with the WHERE clause, when performing and update or delete operation.
CHANGED_COLUMNS – EclipseLink compares only the changed fields in the WHERE clause when performing an update.
SELECTED_COLUMNS – EclipseLink compares the selected field in the WHERE clause when performing and update or delete operation on the SelectedColumns.
VERSION_COLUMN – EclipseLink compares a single version number in the WHERE clause when performing an update.

VERSION_COLUMN

Usage

You can specify @OptimisticLocking on an Entity or MappedSuperclass.

Examples

Example 2-83 shows how to use the @OptimisticLocking annotation for all columns

Example 2-83 Using @OptimisticLocking Annotation

@Table(name = "EMPLOYEES")
  @OptimisticLocking(type=OptimisticLockingType.ALL_COLUMNS)
  public class Employee implements Serializable {
      ...
  }

Example 2-83 shows how to use the <optimistic-locking> element in the eclipselink-orm.xml file for a single column.

Example 2-84 Using <optimistic-locking> XML

<entity name="Employee" class="my.Employee" access="PROPERTY" change-tracking="DEFERRED">
...
    <optimistic-locking type="SELECTED_COLUMNS" cascade="false">
      <selected-column name="id"/>
      <selected-column name="firstName"/>
    </optimistic-locking>
...
</entity>

See Also

For more information, see:

"Scaling EclipseLink Applications in Clusters" in Solutions Guide for EclispeLink