EclipseLink/UserGuide/JPA/Basic JPA Development/Caching/Query Options

EclipseLink JPA

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Key API

• QueryHints

Native API

• DatabaseQuery
• ReadAllQuery
• ReportQuery

Query Options and In-memory Querying

The EclipseLink query results cache allows the results of named queries to be cached, similar to how objects are cached.

Configuring Query Results Cache

The query results cache is configured through query hints.

Query Results Cache Query Hints

Hint	Description	Default	Required?
eclipselink.query-results-cache	Enable query results cache for the named query.	no cached results	Required
eclipselink.query-results-cache.size	Sets the fixed size of the query results cache for the named query. The size is the number of queries with unique parameters to cache. If the query has no parameters, a value of 1 should be used.	100	Optional
eclipselink.query-results-cache.expiry	Sets the expiry time in milliseconds of the cached results.	no expiry	Optional
eclipselink.query-results-cache.expiry-time-of-day	Configures the time of day expiry. Valid values are string time format, "HH:MM:SS".	no expiry	Optional
eclipselink.query-results-cache.randomize-expiry	Set if the expiry time should be randomized by 10% of the set expiry time. This can be used to avoid a bottleneck on a fixed expiry time.	false	Optional
eclipselink.query-results-cache.type	Set the cache type. Valid values are defined in the CacheType enum. Normally an LRU fixed sized CACHE is used, a FULL, WEAK or SOFT cache can also be used.	CACHE	Optional

In-memory query example

Query query = em.createQuery("Select e from Employee e where e.firstName like :firstName and e.lastName like :lastName");
query.setParameter("firstName", "B%");
query.setParameter("lastName", "S%");
List<Employee> employees = query.getResultList();

Version: 2.4 DRAFT
Other versions...

Query Results Cache	Caching	Clustering and Cache Coordination
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