Notice: This Wiki is now read only and edits are no longer possible. Please see: https://gitlab.eclipse.org/eclipsefdn/helpdesk/-/wikis/Wiki-shutdown-plan for the plan.
Difference between revisions of "EclipseLink/UserGuide/JPA/2.4/a batchfetch"
m (New page: {{EclipseLink_TLJPA |info=n |toc=n |category=JPA |release=2.4.x}} <span class="metaname"> </span> {| class="simple oac_no_warn" width="100%" | align="left" valign="top" | '''Java Pers...) |
m |
||
| Line 3: | Line 3: | ||
|toc=n | |toc=n | ||
|category=JPA | |category=JPA | ||
| − | |release=2.4.x}} | + | |release=2.4.x |
| + | |title= }} | ||
<span class="metaname"> </span> | <span class="metaname"> </span> | ||
{| class="simple oac_no_warn" width="100%" | {| class="simple oac_no_warn" width="100%" | ||
| − | | align="left" valign="top" | | + | | align="left" valign="top" | |
| width="144" align="right" valign="bottom" | | | width="144" align="right" valign="bottom" | | ||
{| class="simple oac_no_warn" width="100%" | {| class="simple oac_no_warn" width="100%" | ||
Revision as of 07:22, 8 June 2012
|
|
@BatchFetch
Use @BatchFetch to read objects related to a relationship mapping (such as one-to-one, one-to-many, many-to-one, many-to-many, and element collection) to be read in a single query.
Annotation Elements
Table 2-1 describes this annotation's elements.
Table 2-1 @BatchFetch Annotation Elements
| Annotation Element | Description | Default |
|---|---|---|
|
size |
Default size of the batch fetch, used only when |
|
|
BatchFetchType |
(optional) The type of batch fetch to use:
|
JOIN |
Usage
Batch fetching allows for the optimal loading of a tree. Setting the @BatchFetch annotation on a child relationship of a tree structure causes EclipseLink to use a single SQL statement for each level.
Examples
Para.
Example 2-1 Using JOIN BatchFetch Type
Example 2-2 Using EXISTS BatchFetch Type
Example 2-3 Using IN BatchFetch Type
See Also
For more information, see:
|
|
|
