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.

Note:

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:

"EclipseLink" JPA Query Hints
http://wiki.eclipse.org/EclipseLink/UserGuide/JPA/Basic_JPA_Development/Querying/Query_Hints
"join-fetch"
"batch.size"
"batch.type"
"Querying" in Solutions Guide for EclispeLink