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EclipseLink/UserGuide/JPA/2.4/a batchfetch
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Beta Draft: 2012-06-18
@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 2-3 describes this annotation's elements.
Table 2-3 @BatchFetch Annotation Elements
| Annotation Element | Description | Default |
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size |
Default size of the batch fetch, used only when |
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BatchFetchType |
(optional) The type of batch fetch to use:
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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
The following examples show how to use this annotation with different batch fetch types.
Example 2-7 Using JOIN BatchFetch Type
Example 2-8 Using EXISTS BatchFetch Type
Example 2-9 Using IN BatchFetch Type
See Also
For more information, see:
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