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that it manages. The persistence context serves as a first level cache . An attempt to retrieve ... context is one  EntityManager . This section describes a level 2  (L2) cache of entity ... . the broader scope of this cache makes it useful in applications that use many short term 

engine settings: The cache attribute is a hint that specifies the amount of memory that is used for caching pages of the database file. The max-threads attribute specifies the maximum number ... of the two cache mechanisms that ObjectDB manages for queries: The results attribute specifies the size

to have my persistent objects be cached until the Java Virtual Machine (JVM) does a full Garbage Collection (GC ... cache .  I disable the L2 cache and use 1 MB for the ObjectDB Datastore page file cache ... , and a soft reference when the byte[] only needs to be read and sits in the cache until more heap RAM

. Configurable - minimum/maximum connections and timeout. Caching L1 entity object cache (per EntityManager). L2 shared entity data cache  (per EntityManagerFactory). Database file page cache . Query program cache (for repeating queries with different arguments). Query result cache (for repeating

after a runtime of several weeks we are now analyzing the usage of the cache and so on. Looking at the heap dump we suspect that the cache is really used (see heap dump attached), the RAM allocated ... . The config is attached as well. The question is: is the cache really used ? hgzwicker Hans-Georg

JPA Interface Cache Interface used to interact with the second-level cache . If a cache is not in ... . Since: JPA 2.0 The Shared (L2) Entity Cache article explains how to use Cache . Public Methods boolean contains (Class cls, Object primaryKey) Whether the cache contains data for the given

. Level 2 JPA cache is activated and it works ok for find by id (tested by changing data in explorer and reading in my app). Problem 1: find by id on Item it's good, it hits the cache , but not for its field ... my app). "user" should also be taken from L2 cache , shouldn't it? Otherwise...it's a huge

Hi, Is there any way to check, if 2 level cache is in use? Right now I've done two things: 1. objectdb.conf with cache size is placed in WEB-INF directory of my web application. 2. persistence.xml ... , so most of the data should be in cache . ODB and Tomcat are on different servers. lwalkowski Lukasz Walkowski

is the same that is cached in 2nd level cache . so that if i request that entity again I will get actually ... on this (is it really the same object kept in cache ).... Now the problem is that I need to have guarantee that this entity object is kept in cache all the time (there are not many of these entities

.conf to give 256KB disk accesses and use PersistenceManager L1 ref=soft caching and datastore pagefile caching 1 MB (4 256KB sized pages).  The goal is to have frequent PersistenceManager L1 cache hit, then less frequent datastore pagefile cache hit, then when absolutely necessary, read/write

Is it possible to configure the second level cache as distributed? The use-case: The object Person "John" is read on application node 1 and also on application node 2 to the second level caches ... level cache on application node 1 has a correct data. The object Person is read from application node

references to such cached result objects ? or do ObjectDB exploits frequency of querying such objects ... memory size of ObjectDB L2 cache or EntityManager context ? Q4: Would paging result sets ... of the persistence context (the EntityManager L1 cache ) but instantiation of the results

Are there some possibilities to configure following caches in order to keep cache data for only some important entity types and for the entire life cycle of the EntityManagerFactory. Cache of database file pages. Cache of query programs. Cache of query execution results. btc_es BTC EmbeddedSystems

Hello! I would like to use selective cache for JPA Level 2 ( cached in EntityManagerFactory) in one app, but no cache at all in another app. Both will be connected to the same ObjectDB server & db ... #The_ cache _element_  specifies only amount of MB used for Level 2 cache , but the config

objectdb.conf has options for query results and program cache .  (objectdb.conf database query- cache results and programs, https://www.objectdb.com/java/jpa/setting/database#The_query- cache ... and program cache still available?   CBE CBE Yes, these are server/store side caches . The exact client side code doesn't affect. support Support

was load and the entity MyEntity1 is taken in the second level cache , the other entity types not ... EmbeddedSystems The 2nd level cache stores object data (byte[]) rather than live entity objects ... ;2nd level cache as object IDs (PK) encoded in the  byte[] of a MyEntity1 instance

JPA Method in javax.persistence. Cache T unwrap (   Class  cls ) Return an object of the specified type to allow access to the provider-specific API. If the provider's Cache ... - the class of the object to be returned. This is normally either the underlying Cache implementation

JPA Method in javax.persistence. Cache boolean contains (   Class cls,    Object primaryKey ) Whether the cache contains data for the given entity. Parameters: cls - entity class primaryKey - primary key Return: boolean indicating whether the entity is in the cache Since: JPA 2.0

attempting to keep the L1 cache within the PersistenceManager cleared in an effort to reduce its memory ... the cache ?   try { // Start the transaction m_persistenceManager.currentTransaction().begin ... .makePersistentAll(addCollection); // Flush the JDO cache m_persistenceManager.evictAll(); m_persistenceManager

JPA Method in javax.persistence. Cache void evictAll () Clear the cache . Since: JPA 2.0

JPA Method in javax.persistence. Cache void evict (   Class cls,    Object primaryKey ) Remove the data for the given entity from the cache . Parameters: cls - entity class primaryKey - primary key Since: JPA 2.0

JPA Method in javax.persistence. Cache void evict (   Class cls ) Remove the data for entities of the specified class (and its subclasses) from the cache . Parameters: cls - entity class Since: JPA 2.0

we have a customer system with 64 GByte RAM, 16 CPUs on 8 sockets, the fastest possible ssd. we wonder if the cache and other settings can be optimized to get the most performance these are the current settings, please advice what we could optimize            

range. Check [Disable Cache ] to bypass query program and result caches . Click the Execute button ... the content of all the fields. Refreshing the Cache When a database is open in the Explorer in ... by another process the viewer windows in the Explorer might display cached content that does not

The element specifies settings of the two cache mechanisms for entities: The ref attribute specifies ... (which serves as a first level cache ). The valid values are "weak" , "soft " and "strong ". Modified ... ), regardless of this setting. The level2 attribute specifies the size of the shared level 2 cache

at it is that the persistence context also functions as a local cache for a given EntityManager . ObjectDB also manages a level 2 shared cache for the EntityManagerFactory as well as other caches as explained in

). This could be useful when the shared L2 cache is enabled and entity objects may already be available in the cache

of the database. The persistence context serves as a cache of retrieved entity objects. If a requested ... with data that is retrieved from the database (or from the L2 cache - if enabled). The new entity object

This section contains miscellaneous JPA types. The PersistenceUtil and PersistenceUnitUtil interfaces provide general utility methods: The Cache interface and the CacheRetrieveMode and CacheStoreMode enum types serve in managing the EntityManagerFactory's shared (level 2) cache : Other enum types are provided for setting of various JPA operations:

that a cached entity object in its persistence context has been removed from the database by

with the same query string and use a cached compiled query program , if available. Secondly

that a cached entity object in its persistence context has been modified by an UPDATE query

JPA defines three types of persistable classes which are set by the following annotations: Chapter 2 of the ObjectDB manual explains these annotations in detail. Entity and mapped super classes can be further configured by annotations that specify cache preferences and lifecycle event listener

a container the updated Entities. Scenario 1 : Disabled L2 Cache , updating elements using UPDATE ... database - Actual result: No changes are visble. Scenario 2 : Disabled L2 Cache , updating elements ... , but it is quite a mystery why " .clear() " has to be called. Scenario 3 : Enabled L2 Cache , updating elements

Page cache File handling produced an java.io.IOException: Negative seek offset

of persistent classes, and to keep them as simple as possible. The Persistent Object Cache As noted ... a persistent object representing that database object. Every PersistenceManager instance manages a cache of persistent objects that are in use by the application. If the cache already contains a persistent

.SharedCacheMode Specifies how the provider must use a second-level cache for the persistence unit. Corresponds to the value of the persistence.xml shared- cache -mode element, and returned as the result of () . Since: JPA 2.0 Enum Constants ALL All entities and entity-related state and data are cached

.CacheStoreMode Used as the value of the javax.persistence. cache .storeMode property to specify the behavior ... The Shared (L2) Entity Cache article explains how to use CacheStoreMode . Enum Constants BYPASS Don't insert into cache . Since: JPA 2.0 REFRESH Insert/update entity data into cache when read from database

whether an entity should be cached if caching is enabled when the value of the persistence.xml caching element ... that the entity and its state must not be cached by the provider. Since: JPA 2.0 The Shared (L2) Entity Cache ... (Optional) Whether or not the entity should be cached . Since: JPA 2.0

JPA Method in javax.persistence.EntityManagerFactory Cache getCache () Access the cache that is associated with the entity manager factory (the "second level cache "). Return: instance of the Cache interface or null if no cache is in use Throws: IllegalStateException - if the entity manager factory has been closed Since: JPA 2.0

-local entity managers or is closed Since: JPA 2.1 Cache getCache () Access the cache that is associated with the entity manager factory (the "second level cache "). Return: instance of the Cache interface or null if no cache is in use Throws: IllegalStateException - if the entity manager factory

.CacheRetrieveMode Used as the value of the javax.persistence. cache .retrieveMode property to specify ... ) Entity Cache article explains how to use CacheRetrieveMode . Enum Constants BYPASS Bypass the cache : get data directly from the database. Since: JPA 2.0 USE Read entity data from the cache

JDOQL queries that you test in the Explorer into your Java code. Refreshing the Cache When a database ... content from the cache that does not reflect the real content in the database. In this case you can refresh the cache and the viewer windows using the "File | Refresh Data" menu command. 9.3 

to enlarge the cache and improve server performance: java -server -Xmx512m com.objectdb.Server start To stop

database consistency, it is recommended that write caching be disabled - at least for the database

checkConsistency () Validates the PersistenceManager cache with the datastore. This method has no effect ... the consistency of instances in the cache against the datastore. An implementation might flush instances as ... , this method obtains a datastore connection and verifies the consistency of the instances in the cache

JDO Interface DataStoreCache Many JDO implementations allow instances to be cached in a second-level cache , and allow direct management of the cache by knowledgeable applications. This interface ... the parameter instance from the second-level cache . Parameters: oid - the object id of the instance to evict

,    boolean validate ) This method locates a persistent instance in the cache ... the cache with the specified JDO identity. The oid parameter object might have been returned by ... in the cache with the same JDO identity as the oid parameter, then this method returns

classes in the cache are first flushed to the datastore. Instances in the cache or brought into the cache ... , instances of affected classes in the cache are refreshed to reflect whether they were deleted from ... the back end, instead of in the cache . If this flag is set to true , an implementation might be able

of affected classes in the cache are first flushed to the datastore. Instances in the cache or brought into the cache as a result of executing one of the deletePersistentAll methods undergo life cycle ... to the application, instances of affected classes in the cache are refreshed to reflect