CRUD Database Operations with JPA

Shows how to use Java/JPA to store, retrieve, update & delete.... SQL combined with the ease of use of object databases and second, a new JPA developer with some experience with SQL can become productive ...


Bulk Delete and Update - best practice?

The attached test creates 1000 large objects and then attempts to delete them all in one go using a DELETE statement. I'm trying to run with -Xmx512m but the test runs out of memory during the delete. The attachment also contains an update test which has similar memory problems. I'm running both tests with the default objectdb.conf. In general is an UPDATE/DELETE statement the most efficient way to update/remove a large number of objects? ... database. In the following test I'm expecting the second row count to be 0 if the database is dropped  but that doesnt seem ...


High memory consumption even after close() of EntityManagerFactory

Hello, we still have memory usage problems. When debugging, we have now observed a case in which the execution of multiple queries increasingly byte array were generated (about 1.5 GB) which from GC could not be released. Not even after the EntityManagerFactory closed. We created a small test with which you can observe similar behavior. The huge memory usage only occurs if we execute the query (line 56 to 61). If we remove this query, all is well. The memory is only released after we re-run a query (on a different database). ... can only be released from the GC after the query to the second database connection is performed (line 92). ...


Recommendation - concurrent access multiple class v

Hi! I've just started to architect a new system, stateless JSON API, which is expected to have very high load and to require more servers for parallel deployments (same app across multiple servers). I am considering using ObjectDB, because of its advantages and easy usage, but I'm afraid that it might get corrupted because the manual says that we must not access ObjectDB with different versions of a class. Let's take the following scenario: #1 2014-02-09 10:15 Hi! I've just started to architect a new system, stateless JSON API, which is expected to have very h ...


Unexpected internal exception during set field of an Embeddable to null

Hello, we get an Unexpected internal exception and have no idea what goes wrong. We can reproduce (mostly) the error in a very big use case. In the big use case and we create and persist millions of SignalValueImpl objects (Embeddables). Partly as in the stack trace an Embeddable contain another Embeddable. It seems like that we can't reproduce the problem in smaller use cases with less objects. Stack trace: ... works once on a attched Object and the second time (another attached Object) it results in the error.   ... another SignalValue. AND yes in our case the second IntegerSignalValueImpl Object, on which we get the Exception, is a ...


Database Connection using JPA

Describes the main JPA interfaces: EntityManagerFactory, EntityManager and EntityTransaction.... method takes a map of persistence unit properties as a second parameter: Map<String, String> properties = new ...


Database Transaction Replayer

Explains how to use the ObjectDB object database Replayer tool to restore recorded Java/JPA/JDO actions.... 1000 When a transaction ID is specified as a second argument the Replayer applies recorded operations only until that ...


Log is almost empty (log level 'trace')

Hi, Using 2.4.6_01 version on Linux (2.6.18, VPS)..  Just wondering what should I suppose to see in a log file with a log level 'trace'/'debug'.. Trying to fix an issue that server version sometimes accidentally quits without any notice.. My log file (independently on whats specified in config file) has only database open/close messages, some query.compiler info but nothing more..  Is that right behaviour? Are there are server statistics API/logs available? Regards, #1 2013-02-08 16:25 Hi, Using 2.4.6_01 version on Linux (2.6.18, VPS)..  Just wondering what should I suppose to ...



The Throwable class is the superclass of all errors and exceptions in the Java language.(Class of java.langClass Throwable)


ORDER BY problem, when String starts with language specific character

Dear all, I have a problem with ORDER BY clause. I have a simple query: select u from User u order by u.name When the name starts with "normal/english" character, records are ordered correctly. But when it starts with language specific character like 'Č', these records are placed after records with normal charaters. So records with 'Č' are after 'Z', but this is not correct, because 'Č' is between 'C' and 'D'. ... 11:14 On a second thought, maybe you don't need 2 fields - name and ...