Custom parameter on OData URL, how to integrate with its architecture

Question

I have a typical InMemory OData Producer from odata4j sample code

public static void main(String[] args) { 

        final InMemoryProducer producer = new InMemoryProducer("InMemoryODataProducer",10); 

        producer.register(ResultRow.class,"Results", Funcs.wrap(new ThrowingFunc<Iterable<ResultRow>>() { 
               public Iterable<ResultRow> apply() throws Exception { 
                     return getResults(>>>>>>>>>myParam<<<<<<<<<<<<<<); 
               } 
        }), "Id"); 

        DefaultODataProducerProvider.setInstance(producer); 
        ODataProducerUtil.hostODataServer("http://localhost:8080/InMemoryODataProducer.svc/");  

        (...)

How can I receive a customParam to use for retrieving concrete results given OData architecture? For instance, let's imagine, I want to specify the database as well with the url and I'd like to call

http://localhost:8014/InMemoryODataProducer.svc/Results?$top=2&$orderby=id---->&(database_schema=)myParam

It's indeed something less expected than a database id, I am not looking for any standard way to specify database in OData but to learn how to pass generic custom params.

Thanks!