db4o Developer Community

Finally we are starting to harvest the fruits of our work on pluggable type handlers. As a first step, please welcome .NET generic collections to the exclusive club of types natively supported by db4o in the upcoming 7.6 build.In principle, .NET generic collections could already be persisted in previous versions, but there was no dedicated ...

patrick_roemer:by pointers in one direction (db4o SODA allows you to pose queries that traverse references in the opposite direction)Please can you put an example of such kind of query (opposite direction..)? And with the use of collections to implement relations, can db4o look into a collection looking for a candidate (for example with SODA) ...

I'm having a problem storing and retrieving an object that contains a HashSet wrapped in a SynchronizedSet, e.g.: class MyClass {   private Set<UniqueID> ids = Collections.synchronizedSet(new HashSet<UniqueID>()); ... }  I can store this object and retrieve it and it will contain the UniqueIDs that I added to the ...

I just found this thread, so I thought I would collect here some questions I had previous posted elsewhere relating to collection needs:Re: equest: lazy activation for collectionshttp://developer.db4o.com/forums/post/45692.aspx- about collections needing to load/activate elements on demand, instead of the entire set:- from the fast collections ...

ObjectContainer.set() is expensive?I was doing some performance tests for a timesheet application I am writing, and was simulating the addition of thousands of item additions through a web service. Ultimately, the logic of the simulation boils down to:  public class Item { int id; String description; Date date; } ... final int ...

Hello. I am a new user to Db4o, quite impressed with its promise of allowing persistence to be programmed in the style of regular OO programming.In an attempt to avoid the need for complex and inefficient queries I am using explicit relationships between objects. E.g. an aspect of my app has to do with timesheets, and for a user I store work ...

My collegue found problem after a few hot days. Deleting not only in collection, but also item in container depends on configuration with generateUUIDs! cascadeOnDelete(false) for team ObjectClass solves this problem, but it's not documented. I have 3 classes Team, Pilot and TeamApp:   import java.util.ArrayList;import ...

Addition: The strange behaviour is with beans in application context, when I use the xml as simple BeanFactory it works like in db4o - item is  removed from collection, but not from container. WHY is such different behaviour?

Handling multiplicity in object databases Collections and arrays introduce new levels of complexity to the structured objects first discussed in The busy Java™ developer's guide to db4o: Beyond simple objects. Fortunately, db4o isn't the least bit fazed by handling multiplicity relationships -- and neither ...

Lets say that Asset contains a List<Calibration> and Calibration has a ''String technician''.  My objective is to find all of the Assets that have Calibrations done by a certain technician.  The query I'm using to solve this seams too slow.  Is there any way to create an index that will help speed this up.  I also tried ...