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| <div class="subTitle">org.eclipse.persistence.annotations</div> |
| <h2 title="Annotation Type FetchGroup" class="title">Annotation Type FetchGroup</h2> |
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| <pre><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Target.html?is-external=true" title="class or interface in java.lang.annotation">@Target</a>(<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Target.html?is-external=true#value--" title="class or interface in java.lang.annotation">value</a>=<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/ElementType.html?is-external=true#TYPE" title="class or interface in java.lang.annotation">TYPE</a>) |
| <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Retention.html?is-external=true" title="class or interface in java.lang.annotation">@Retention</a>(<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Retention.html?is-external=true#value--" title="class or interface in java.lang.annotation">value</a>=<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/RetentionPolicy.html?is-external=true#RUNTIME" title="class or interface in java.lang.annotation">RUNTIME</a>) |
| <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Repeatable.html?is-external=true" title="class or interface in java.lang.annotation">@Repeatable</a>(<a href="https://docs.oracle.com/javase/8/docs/api/java/lang/annotation/Repeatable.html?is-external=true#value--" title="class or interface in java.lang.annotation">value</a>=<a href="../../../../org/eclipse/persistence/annotations/FetchGroups.html" title="annotation in org.eclipse.persistence.annotations">FetchGroups.class</a>) |
| public @interface <span class="memberNameLabel">FetchGroup</span></pre> |
| <div class="block">A fetch group is a performance enhancement that allows a group of attributes |
| of an object to be loaded on demand, which means that the data for an |
| attribute might not loaded from the underlying data source until an explicit |
| access call for the attribute first occurs. It avoids the wasteful practice |
| of loading up all data of the object's attributes, in which the user is |
| interested in only partial of them. |
| |
| A great deal of caution and careful system use case analysis should be use |
| when using the fetch group feature, as the extra round-trip would well offset |
| the gain from the deferred loading in many cases. |
| |
| EclipseLink fetch group support is twofold: the pre-defined fetch groups at |
| the Entity or MappedSuperclass level; and dynamic (use case) fetch groups at |
| the query level. |
| |
| Fetch groups can only be used when weaving is enabled or when individual |
| classes that define them explicitly implement the |
| org.eclipse.persistence.queries.FetchGroupTracker interface.</div> |
| <dl> |
| <dt><span class="simpleTagLabel">Author:</span></dt> |
| <dd>Guy Pelletier</dd> |
| <dt><span class="simpleTagLabel">Since:</span></dt> |
| <dd>EclipseLink 2.1</dd> |
| </dl> |
| </li> |
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| <!-- =========== ANNOTATION TYPE REQUIRED MEMBER SUMMARY =========== --> |
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| <h3>Required Element Summary</h3> |
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| <caption><span>Required Elements</span><span class="tabEnd"> </span></caption> |
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| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Required Element and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><code><a href="../../../../org/eclipse/persistence/annotations/FetchAttribute.html" title="annotation in org.eclipse.persistence.annotations">FetchAttribute</a>[]</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/eclipse/persistence/annotations/FetchGroup.html#attributes--">attributes</a></span></code> |
| <div class="block">(Required) The list of attributes to fetch.</div> |
| </td> |
| </tr> |
| <tr class="rowColor"> |
| <td class="colFirst"><code><a href="https://docs.oracle.com/javase/8/docs/api/java/lang/String.html?is-external=true" title="class or interface in java.lang">String</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/eclipse/persistence/annotations/FetchGroup.html#name--">name</a></span></code> |
| <div class="block">(Required) The fetch group name.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
| </ul> |
| <!-- =========== ANNOTATION TYPE OPTIONAL MEMBER SUMMARY =========== --> |
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| <h3>Optional Element Summary</h3> |
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| <caption><span>Optional Elements</span><span class="tabEnd"> </span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Optional Element and Description</th> |
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| <tr class="altColor"> |
| <td class="colFirst"><code>boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../org/eclipse/persistence/annotations/FetchGroup.html#load--">load</a></span></code> |
| <div class="block">(Optional) Indicates whether all relationship attributes |
| specified in the fetch group should be loaded.</div> |
| </td> |
| </tr> |
| </table> |
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| <h4>name</h4> |
| <pre>public abstract <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/String.html?is-external=true" title="class or interface in java.lang">String</a> name</pre> |
| <div class="block">(Required) The fetch group name.</div> |
| </li> |
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| <h4>attributes</h4> |
| <pre>public abstract <a href="../../../../org/eclipse/persistence/annotations/FetchAttribute.html" title="annotation in org.eclipse.persistence.annotations">FetchAttribute</a>[] attributes</pre> |
| <div class="block">(Required) The list of attributes to fetch.</div> |
| </li> |
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| <h4>load</h4> |
| <pre>public abstract boolean load</pre> |
| <div class="block">(Optional) Indicates whether all relationship attributes |
| specified in the fetch group should be loaded.</div> |
| <dl> |
| <dt>Default:</dt> |
| <dd>false</dd> |
| </dl> |
| </li> |
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