Updating Db4o File Format

The db4o database file format is a subject to change to allow progress for performance and additional features.

db4o does not support downgrades back to previous versions of database files.

In order to prevent accidental upgrades when using different db4o versions or ObjectManager, db4o does not upgrade databases by default.

Database upgrading can be turned on with the following configuration switch:

Java: 

Db4o.configure().allowVersionUpdates(true)

Please note that, once the database file version is updated, there is no way to get back to the older version of the database file

If a database file is opened successfully with the new db4o version, the upgrade of the file will take place automatically. You can simply upgrade database files by opening and closing a db4o database once with code like the following:

UpdateExample.java
01/* Copyright (C) 2007 db4objects Inc. http://www.db4o.com */ 02 03package com.db4odoc.versionupdate; 04 05import com.db4o.Db4o; 06import com.db4o.ObjectContainer; 07 08public class UpdateExample { 09 10 public static void main(String[] args) { 11 Db4o.configure().allowVersionUpdates(true); 12 ObjectContainer objectContainer = Db4o.openFile(args[0]); 13 objectContainer.close(); 14 System.out.println("The database is ready for the version " + Db4o.version()); 15 } 16 17}

Recommendations for upgrading: