About weak
Entity Management Settings
Explains settings and performance tuning of JPA entities in ObjectDB, the fast Java object database for JPA/JDO.... = "warning" /> <cache ref = "weak" level2 = "0mb" /> <persist serialization = ... <cache> element <cache ref = "weak" level2 = "0mb" /> The <cache> element ...
Entity Management Config questions
Hi, the manual states the following regarding config of Entities: http://www.objectdb.com/java/jpa/setting/entities : <cache ref="weak" level2="0mb" /> The <cache> element specifies settings of the two cache mechanisms for entities:... : <cache ref = "weak" level2 = "0mb" /> The <cache> element ... serves as a first level cache). The valid values are "weak" , "soft " and "strong " . Modified entities are always ... Question : What exactly is the difference between "weak", "soft", and "strong" references? ...
Working with JPA Entity Objects
Explains the entity object lifecycle and the persistence context.... a transaction are held in the persistence context by weak references. Therefore, when a managed entity object is no longer in use by ... to use strong references or soft references instead of weak references . The contains method can check if a specified ...
Is ObjectDB a NoSQL Database?
... and limitations of NoSQL technology, which are weak query capabilities and lack of ACID (atomicity, consistency, isolation, ...
Storing Images and Object Pooling
Hello we have heard your product and we will plan to use your product on image database. Is it good to use ObjectDB as image database? Image database just screenshots of desktops. 2- ) On JPA as we know getting Result list returns ArrayList List<SomeClass> xxx = query.getResultList(); ... the default reference cache configuration from weak to soft or strong. However, notice that objects are cached as objects per ...
Caching/Paging Questions...
Greetings ObjectDB team, All below questions assume a very large database (~1,000,000,000 objects): Q1: Two queries with a big overlap between their result sets. If I query the first set and hold the results in memory somehow, would that speed up the execution of the second query since many of its result objects already created and reside in memory ?... soft references, which are something in the middle between weak and strong references. The size of the L1 cache is automatic. There ...
Connection is closed Caused by: java.io.EOFException
I am getting this exception on a regular basis, after a period of time of repeating the same code execution. I don't understand why. I restart the DB server and my code works again for another period of time until same exception is encountered again. I cannot pin down a pattern e.g. after a certain period of time, because the time periods between exceptions are not regular, although frequent. Any test case I use will pass most of the time but will fail after an undetermined period. ... = "warning" /> <cache ref = "weak" level2 = "0" /> <cascade-persist always = ...
evictAll() behavior
I'm writing a multi-user drawing tool, using objectdb as the central store. When a user press F5, I want to pick up all the changes from the database. So, I call evictAll() in the following ways: pmf.getDataStoreCache().evictAll(); // the factory pm.evictAll(); // the persistence manager A couple of questions about this: 1. the first evictAll() seems to be clearing the L2 cache -- is this correct 2. the evicts only work when they are done inside a transaction -- is this specified in the JDO spec?... - i could use makeTransient but if the L2 cache is using weak references I should not get OutOfMemory exception, Im adding ...
OneToMany and cascade delete problem
Hi, I don't really know if this is a bug or maybe model that I make is bad. I have a problem with with two different classes with OneToMany relation to one, shared class. For example (first class): @Entity public static class Store { @OneToMany(targetEntity = Offer.class, mappedBy = "store") private List<Offer> offers; } second class: ... as in this case in reflection mode (with enhancement, weak references are used more intensively, so Product instances are removed ...
[ODB1] Chapter 6 - Persistent Objects
Shows how to store, retrieve, update and delete database objects. ... or deleted during a transaction are held in the cache by weak references. Therefore, when a persistent object is no longer in use by the ...
