4 JPA Query Customization Extensions

You can specify EclipseLink query hints (JPA query extensions) by:

• Using the @QueryHint annotation

• Including the hints in the orm.xml or eclipselink-orm.xml file

• Using the setHint() method when executing a named or dynamic query (JPQL or Criteria)

EclipseLink supplies the following query hints:

• batch

• batch.size

• batch.type

• cache-usage

• cache-usage.indirection-policy

• composite-unit.member

• cursor

• cursor.initial-size

• cursor.page-size

• exclusive-connection

• fetch-group

• fetch-group.attribute

• fetch-group.default

• fetch-group.load

• fetch-group.name

• flush

• history.as-of

• history.as-of.scn

• inheritance.outer-join

• jdbc.allow-native-sql-queries

• jdbc.bind-parameters

• jdbc.cache-statement

• jdbc.fetch-size

• jdbc.first-result

• jdbc.max-rows

• jdbc.native-connection

• jdbc.parameter-delimiter

• jdbc.timeout

• join-fetch

• left-join-fetch

• load-group

• load-group.attribute

• maintain-cache

• partitioning

• pessimistic-lock

• prepare

• query-results-cache

• query-results-cache.expiry

• query-results-cache.expiry-time-of-day

• query-results-cache.ignore-null

• query-results-cache.randomize-expiry

• query-results-cache.size

• query-results-cache.type

• query-type

• query.redirection

• read-only

• refresh

• refresh.cascade

• result-collection-type

• sql.hint

All EclipseLink query hints are defined in the QueryHints class in the org.eclipse.persistence.config package. When you set a hint, you can set the value using the public static final field in the appropriate configuration class in org.eclipse.persistence.config package, including the following:

• HintValues

• CacheUsage

• PessimisticLock

• QueryType

For more information, see Section 10.3.1 "NamedQuery Annotation" in the JPA Specification (http://jcp.org/en/jsr/detail?id=317).