About memory

manual

[ODB1] Chapter 7 - JDOQL Queries

Explains how to use JDOQL, the Java/JDO Query Language.... an Extent . It is useful for filtering a collection in memory, and for requerying the result of a previous JDOQL query. A ...

 
forum_thread

using DbUnit with ObjectDb

Are there any examples about how to use DbUnit with ObjectDB? DbUnit requires access to a jdbc connection .. with other providers it's possible to extract the jdbc connection from the EntityManager, e.g. for Eclipselink / Postgres combination you can use the rather long-winded: IDatabaseConnection connection = new DatabaseConnection(((EntityManagerImpl) (em2.getDelegate())).getServerSession().getAccessor().getConnection(), "PUBLIC"); but with objectDb this gives: ... is limited to small data sets that can fit into the main memory, doesn't it? Can you use it to load many GBs of data? If you load ...

 
forum_thread

Issue with orphanRemoval and multiple EntityManagers

Hi, We have a problem where our database size grows over time more than expected. We've traced it down to the following issue: ... classes are much more efficient in performance and in memory consumption, so it is highly recommended to use only enhanced classes in ...

 
manual

FROM clause (JPQL / Criteria API)

Explains how to use the FROM clause and JOIN expressions in a JPA/JPQL query.... illusion that all the database objects are available in memory for navigation. But this feature could also cause performance problems. ...

 
manual

Index Definition

Describes how to define indexes in JPA entity classes and explains how indexes are used in JPQL queries.... that ObjectDB maintains in the file system rather than in memory. The keys of the BTree are all the unique values in the indexed field ...

 
manual

Database Management Settings

Explains settings and performance tuning of the ObjectDB Java object database for JPA/JDO.... attribute is a hint that specifies the the amount of memory that is used for caching pages of the database file. The ...

 
issue

Exception in thread "ODB-StoreHandler-5094" java.lang.NullPointerException

Hi, ... may be some impact over time (but not necessaraly) on memory consumption and socket usage, but this could be negligible. ...

 
forum_thread

One transaction or two?

If I have a large number of objects to delete and then add to a PersistenceManager is it more efficient to do everything in one transaction or two? Currently my code looks like this: ... On the hand such a solution is expected to consume more memory. Since you are asking about add/remove operations rather than ...

 
manual

SELECT clause (JPQL / Criteria API)

Explains how to use the SELECT clause and projections in a JPA/JPQL query.... lightweight, they are built faster and they consume less memory. SELECT DISTINCT Queries that use projection may return ...

 
issue

Navigation through lazy loading from Detached Objects

A main limitation of detached objects (as explained on the Detached Entities manual page) is: ... effect is unclear yet, but for example, it could affect memory consumption and file closing if detached objects (which are not detached ...