Specifications :: db4o V7.0

• Platforms
• Languages
• Commands
• Transparency
• Query Languages / APIs
• Modes / Concurrency
• Scalability and Performance
• Replication
• Reporting
• Security and Encryption
• Availability, Reliability, Zero-Admin
• Internationalization
• Refactoring
• Memory and file size

Platforms

Java	J2EE J2SE J2ME with reflection: CDC, PersonalProfile, Symbian, JavaFX Mobile and Zaurus; on demand(2): J2ME w/o reflection (CLDC and MIDP), including RIM/Blackberry and Palm OS. Android (Open Handset Alliance) Harmony Supported Frameworks: Spring, OSGi, Tomcat, DataNucleus
.NET	.NET Framework (1.0(1), 2.0, 3.0, 3.5) .NET Compact Framework 1.0(1), 2.0 Windows (XP, Vista) Windows Mobile / PocketPC Mono(1) Supported Frameworks: Castle, Eiffel, Spring.net
Cross-platform	Connect to .NET server with Java client Connect to Java server with .NET client

Languages

Java	JDK 1.1.x - JDK 6.0
.NET	All managed .NET languages (C#, VB.NET, ASP.NET, Boo, Managed C++ etc.)

Commands

Sessions	Start and end
Database files	Create, open, close, and delete
Transactions	Commit and Rollback
Objects	Store, retrieve, update (incl. cascaded), replicate, delete (incl. cascaded)
Messaging	TCP/IP

Transparency

Language constructs	Primitive types Strings Arrays Multi-dimensional arrays Inner classes Java/C# collections Classes without public constructors .NET structs Blobs (stored outside of DB file)
Non-Intrusive	Without deriving from a specific base class Without implementing a specific interface Without modifications to source code Without implementing Serializable
Private Fields	Storable
File I/O	Pluggable
Reflector	Pluggable Generic
Aliases	Class aliasing for class-to-class mappings

Query Languages / APIs

Object oriented	Native Queries (NQ) LINQ Query By Example (QbE) S.O.D.A.
SQL	Via replication to many relational databases
XML	With Third-Party products (e.g., Xstream)

Modes / Concurrency

Operation Modes	Local Client/Server
Threads	Multiple
Transactions	Multiple, parallel
Semaphores	Available
Read-Only Mode	Available

Scalability and Performance

Performance benchmark	Up to 55x faster than Hibernate/MySQL
Examples of Scalability	Stores 200,000 objects/second Stores 300,000 objects on a PDA
In Memory Mode	Available
Client-side	Single-process execution available
Server-side	Server-side query execution available
DB-aware Collections	Available
Object Caching	Available
Pagination	Server-side cursors (lazy queries)
Indexing	BTree field indexes BTree query processor

Replication

db4o Replication System (dRS)	100% object-oriented: simply replicate objects, not tables Uni- and bi-directional db4o to db4o db4o to relational databases (RDBMS), wrapped in Hibernate (Java only) Hibernate/RDBMS to Hibernate/RDBMS (Java only)
UUID	Unique Universal Identity over all DB instances
Synchronization	Querying Update Delete Conflict resolution

Reporting

For Java objects	Actuate BIRT Elixir Report Jaspersoft JasperReports Jinfonet JReport
For .NET objects	Microsoft Visual Studio 2005 - ReportViewer

Security and Encryption

DB file Protection	Password
DB file Encryption	Simple database encryption Pluggable File I/O for custom encryption With Third-Party products (e.g., XTEA)

Availability, Reliability, Zero-Admin

Transactions	ACID Commit-recovery on system failures
Thread Safety	Available
Automatic Recovery	Available
Online-Backup	Available
Free Space Management	Available

Internationalization

Unicode

Available

Refactoring

Schema Versioning	Automatic recognition and maintenance
Schema Merge	Available
Renaming	Classes, fields by API Access to values of removed fields by API or with ObjectManager UI

Memory and file size

DB library footprint	<1 MB Small footprint (~600k) available on demand(2)
Minimal RAM footprint	Application dependent; deterministic; below 3 MB for all but one PolePosition benchmark (www.polepos.org)
Maximum DB file size	254 GB / database file
Class size	No increase when persisted
Instance size	No increase when persisted

(1) available through 3rd party providers or db4o developer community projects
(2) available on demand, built to order against services contract