query-results-cache

Use eclipselink.query-results-cache to specify that the query should use a results cache.

Values

Table 4-27 describes this persistence property's values.

Table 4-27 Valid Values for query-results-cache

Value	Description
`Persistence_Unit_Default`	(Default)
`True`	Query results are cache.
`False`	Query results are not cached.

Usage

By default, the query will cache 100 query results (see query-results-cache.size); if the same named query with the same arguments is re-executed EclipseLink will skip the database and return the cached results.

Note:

The query cache is different and independent from the object cache.

Examples

Example 4-54 Using query-results-cache in a JPA Query

import org.eclipse.persistence.config.HintValues;
 import org.eclipse.persistence.config.QueryHints;
 query.setHint("eclipselink.QUERY_RESULTS_CACHE", "TRUE");

Example 4-55 Using query-results-cache in a @QueryHint Annotation

import org.eclipse.persistence.config.HintValues;
 import org.eclipse.persistence.config.QueryHints;
 @QueryHint(name=QueryHints.QUERY_RESULTS_CACHE, value="TRUE");

Example 4-56 Using query-results-cache in orm.xml File

<?xml version="1.0"?>
<entity-mappings
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/orm"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.eclipse.org/eclipselink/xsds/persistence/orm     http://www.eclipse.org/eclipselink/xsds/eclipselink_orm_2_4.xsd"
    version="2.4">
    <entity name="Employee" class="org.acme.Employee" access="FIELD">
        <named-query name="findAllEmployeesInCity" query="Select e from Employee e where e.address.city = :city">
            <hint name="eclipselink.query-results-cache" value="true"/>
            <hint name="eclipselink.query-results-cache.size" value="500"/>
        </named-query>
        ...
    </entity>
</entity-mappings>

See Also

For more information, see:

"About Query Results Cache" in Understanding EclipseLink