Visit the new documentation for updated content. DB4O. Table of contents. 1 Info; 2 The Basic Principle of db4o; 3 Downloads; 4 Current Status. This tutorial was written to get you started with db4o as quickly as possible. Before you The API documentation for db4o is supplied as a compiled Help file . db4o provides sources of documentation: tutorial, reference documentation, API documenation, online paircasts and.

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If you encounter an object that is not yet activated, you can pass it to db4o for manual late activation:.

Queries, updates, and identity

Setting the ActivationDepth to int. December Learn how and when to remove this template message.

Setting the UpdateDepth to 0 will prevent any changes from being saved to the database. Development version provides the newest features and is released for testing, community feedback and evaluation.

Running db4o from the GAC is not supported. The dicumentation option is to create a query language that can then be used to query the database’s object model. MaxValue will cause all related objects to be instantiated as deeply as possible, restoring the entire object graph to memory.

The busy Java developer’s guide to db4o http: When db4o is searching all the objects of the Person type for a given target an oversimplification of what happens, but conceptually accurateto determine if a particular object in the data store meets the criteria, the field values are compared one by one. From Wikipedia, the free encyclopedia. About this series Information storage and retrieval has been nearly synonymous with RDBMS for about a decade now, but recently that has begun to change.

In this particular case, let’s assume that the uniqueness of a Person in the system is its first name-last name combination. This page was last edited on 24 Decemberat It consists of three fields and some basic methods to support POJO-like activities, namely toString and equals.


Developers can find this out, but only in a passive fashion, using the listeners described in this section.

Native queries provide a powerful way to execute complex queries without having to learn a new query language or resort to complicated object structures to model a predicate. An iterator is created against the best index found.

Information storage and retrieval has been nearly synonymous with RDBMS for about a decade now, but recently that has begun to change. Best for limited resource environments.

The default value of 5 is a good balance for most applications, but developers should balance this against the weight of their classes and their access patterns. While a db4o database file is open, it is locked and cannot be accessed by another application at the same time. This content is part of the series: Ted Neward Published on March 27, For example, including a console print statement System.

If you wish to cancel or roll back any uncommitted changes, use the Rollback method:.

The busy Java developer’s guide to db4o: Queries, updates, and identity

Native Query results can be sorted by using an IComparer or a comparison delegate. This is probably the trickiest part of working with an OODBMS because an object database uses a different notion of identity from a relational database. For collection nodes, matches will contain the specified value. Optimization is still done inside the database, but instead of text being returned real objects are sent back, ready for use.

SODA doxumentation expressions are a standard that was present in all but the earliest versions of db4o. A similar documentaion would occur if the persons.

DefragmentConfig (db4o – database for objects – documentation)

By using this site, you agree to the Terms of Use and Privacy Policy. Query Evaluation Mode This property controls when and how much of a query is executed. Included in the db4o distribution you’ll find the installer for ObjectManager Enterprise OME which, once installed, will integrate into your Visual Studio Environment and allow you to open and inspect, query, and edit value types only object instances stored in your database file.


If you haven’t already done so, you may want to download db4o now. Retrieved March 17, It can run on any operating system that supports Java or.

This article contains content that is written like an advertisement. OpenFile [config], [filename] ; The IConfiguration object must be passed in the call to open the db4o file, server, or client connection. When the environment is configured to run with reduced trust, documentatino basic database operations require at least ReflectPermission MemberAccess and ReflectionEmit for the classes and types being persisted. Microsoft Visual Studio Express editions are available for free download from Microsoft.

Getting Started With db4o

To do this, db4o will reflect all of the properties of the object and assemble all non-default property values into a single query expression. NQ can do all this because they are expressed as native. Methods available on this class vary from release to release as they are introduced, removed, or moved to docummentation core ObjectContainer class itself. We said earlier that when calling Store to update an object graph, that documenfation will not by default descend into child objects to detect changes to the graph.

This content is part of in the series: Using Port 0 for your server creates an “Embedded” server which will not be available remotely.

For strings, matches will start with the supplied value. Thus, db4o needs no separate installation mechanism, but comes as a single library file with a footprint of around kB in the.