Unicode

.NET: 

configuration.Unicode(false)

Advantage

Turning Unicode support off reduces the file storage space for strings by factor 2 and improves performance.

Effect

Enables/disables Unicode string storage format. Unicode allows you to store string data in any language to db4o.

This method needs to be called before a database file is created. db4o database files keep their string format after creation.

The default setting is true

Alternate Strategies

You can create your own string marshallers using ObjectMarshaller interface:

.NET: 

Db4oFactory.Configure().ObjectClass(typeof(YourClass)).MarshallWith(yourMarshaller);

Note that custom marshallers have serious limitations.