db4o Developer Community

is it safe to use transparent Activation/Persistence with Version 7.2 ? I want to use db4o for educational purposes, and I do not want to get into problems, that do not originate in the students'  code. Ingeborg Liedlbauer    

I have a confession. Not only am I new to db4o, but to programming in general, Java or otherwise. So please pardon me in advance for this question about transactions. I need to display queried objects in a jsp. Is there a way to do this without keeping the container open for the entire life of the thread? How is this normally done? Does one open ...

I wrote a unit test that includes a Linq query against a db40 IObjectContainer. This passed. I wrote a unit test that traverses a deep object graph and so tests for transparent activation (TA). This failed I enabled my test assembly for TA by adding the post-build command : $(ProjectDir)/Library/Db4oTool.exe -ta -nq ...

Hi,  another question, when I set maximumActivationDepth to 1 on Class B (other classes need it to be 2, therefore my default setting is 2), whenever I call activate(instanceOfB, 5) how deep will it activate? I thought activation it manually would go beyond that limit set, but actually it did not in my case... any other way to activate ...

To address Anat's questions: I would like our efforts to address all of the key areas Anat cites: activation (e.g. bringing an object from persistent storage into main memory), indexing, unique constraints, synchronization, and replication. I believe we will be on the right path if we can define the semantics of these things in abstract terms, ...

To start with, my setup is: db4o version: 6.3jars: db4o-6.3-java5.jar, db4o-6.3-nqopt.jar, bloat-1.0.jarjava version: 1.5.0_04 My application has no real memory constraints, I only have ~ 20000 objects. I was hoping that I could easily run a query and fetch ~ 11000 of those objects quite quickly, but i am seeing fetch times of about 10 seconds. ...

Hi, I had problem with activating object and its callback. I don't know if behaviour of activating is correct. Originall snippet of code: Pilot jan = new Pilot(''Jan'', null);this.db.set(jan); this.db.ext().activate(jan, 1);     //I'm trying to activate object, which was stored into db. Why after setting to db the object ...

Hi,  I have an object with three arrayLists.  This arrayList contain simple objects.  The only issue is the arraylist may contain many objects.  What I mean is the object is already decomposed into simple ones, the only issue is that is has to be related to many other simple objects.  What I want to do is activate only ...

Hi,  I have a large object with some large arraylists.  I want to activate only the arraylist I need at a certain time, add/delete some objects and the update this activated part of the object without the need of activating the rest of the attributes.  I have found that if I do this the unactivated arraylists are set to null. I ...

Thank you for your reply! However despite my best efforts I am still unable to reproduce the behaviour the links, you provided, explain or at the very least unable to verify that it is taking place. I've tried setting ActivationDepth to both 0 and 1 and set the EvaluationMode to Lazy and from what I can tell my entire object graph is still ...