org.eclipse.persistence.config

Class FlushClearCache

java.lang.Object

org.eclipse.persistence.config.FlushClearCache

public class FlushClearCache
extends Object

FlushClearCache persistence property defines modes of cache handling after em.flush call followed by em.clear call. This property could be specified while creating either EntityManagerFactory (createEntityManagerFactory or persistence.xml) or EntityManager (createEntityManager); the latter overrides the former.

JPA persistence property Usage:

properties.add(PersistenceUnitProperties.FLUSH_CLEAR_CACHE, FlushClearCache.Drop);

Values are case-insensitive. "" could be used instead of default value FlushClearCache.DEFAULT.

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT
static String	Drop Call to clear method causes to drop the whole EntityManager cache.
static String	DropInvalidate Call to clear method causes to drops the whole EntityManager cache, on commit the classes that have at least one object updated or deleted are invalidated in the shared cache.
static String	Merge Call to clear method causes to drop from EntityManager cache only the objects that haven't been flushed.

Constructor Summary

Constructors

Constructor and Description
FlushClearCache()

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

Merge

public static final String Merge

Call to clear method causes to drop from EntityManager cache only the objects that haven't been flushed. This is the most accurate mode: shared cache is perfect after commit; but the least memory effective: smbd repeatedly using flush followed by clear may eventually run out of memory in a huge transaction.

See Also:

Constant Field Values

Drop

public static final String Drop

Call to clear method causes to drop the whole EntityManager cache. This is the fasteset and using the least memory mode - but after commit the shared cache potentially contains stale data.

See Also:

Constant Field Values

DropInvalidate

public static final String DropInvalidate

Call to clear method causes to drops the whole EntityManager cache, on commit the classes that have at least one object updated or deleted are invalidated in the shared cache. This is a compromise mode: potentially a bit slower than drop, but has virtually the same memory efficiency. After commit all potentially stale data is invalidated in the shared cache.

See Also:

Constant Field Values

DEFAULT

public static final String DEFAULT

See Also:

Constant Field Values

Constructor Detail

FlushClearCache

public FlushClearCache()