Java Persistence API (JPA) Extensions Reference for EclipseLink, Release 2.4
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batch

Use eclipselink.batch to supply EclipseLink with batching information so subsequent queries of related objects can be optimized in batches, instead of being retrieved one-by-one or in one large joined read.


Values

This query hint accepts a single-valued, relationship path expression.


Usage

Using the eclipselink.batch hint is more efficient than joining, because EclipseLink avoids reading duplicate data.

You can only batch queries that have a single object in the select clause.

Valid values: a single-valued relationship path expression.


NoteNote:

Use dot notation to access nested attributes. For example, to batch-read an employee's manager's address, use e.manager.address.



Examples

Example 4-1 shows how to use this hint in a JPA query.

Example 4-1 Using batch in a JPA Query

import org.eclipse.persistence.config.HintValues;
 import org.eclipse.persistence.config.QueryHints;
 query.setHint("eclipselink.batch", "e.address");

Example 4-2 shows how to use this hint with the @QueryHint annotation.

Example 4-2 Using batch in a @QueryHint Annotation

import org.eclipse.persistence.config.HintValues;
 import org.eclipse.persistence.config.QueryHints;
 @QueryHint(name=QueryHints.BATCH, value="e.address");


See Also

For more information, see: